Error in services after installing

The following services do not start:
FTP Server

 pure-ftpd.service - Pure-FTPd FTP server
   Loaded: loaded (/usr/lib/systemd/system/pure-ftpd.service; enabled; vendor preset: disabled)
   Active: failed (Result: timeout) since Fri 2020-08-07 09:29:01 UTC; 17s ago
  Process: 20770 ExecStart=/usr/sbin/pure-config.pl /etc/pure-ftpd/pure-ftpd.conf --daemonize (code=exited, status=0/SUCCESS)

Aug 07 09:27:31 srv systemd[1]: Starting Pure-FTPd FTP server...
Aug 07 09:27:31 srv systemd[1]: Can't open PID file /var/run/pure-ftpd.pid (yet?) after start: Too many levels of symbolic links
Aug 07 09:29:01 srv systemd[1]: pure-ftpd.service start operation timed out. Terminating.
Aug 07 09:29:01 srv systemd[1]: Failed to start Pure-FTPd FTP server.
Aug 07 09:29:01 srv systemd[1]: Unit pure-ftpd.service entered failed state.
Aug 07 09:29:01 srv systemd[1]: pure-ftpd.service failed.

Mail services:
Dovecot

dovecot.service - Dovecot IMAP/POP3 email server
   Loaded: loaded (/usr/lib/systemd/system/dovecot.service; enabled; vendor preset: disabled)
   Active: activating (start) since Fri 2020-08-07 09:29:10 UTC; 36s ago
     Docs: man:dovecot(1)
           http://wiki2.dovecot.org/
  Process: 22156 ExecStart=/usr/sbin/dovecot (code=exited, status=0/SUCCESS)
  Process: 22153 ExecStartPre=/usr/sbin/portrelease dovecot (code=exited, status=0/SUCCESS)
  Process: 22149 ExecStartPre=/usr/libexec/dovecot/prestartscript (code=exited, status=0/SUCCESS)
   CGroup: /system.slice/dovecot.service
           ├─22158 /usr/sbin/dovecot
           ├─22159 dovecot/anvil
           ├─22160 dovecot/log
           └─22162 dovecot/config

Aug 07 09:29:10 srv systemd[1]: Starting Dovecot IMAP/POP3 email server...
Aug 07 09:29:10 srv systemd[1]: Can't open PID file /var/run/dovecot/master.pid (yet?) after start: Too many levels of symbolic links

AMaViS

amavisd.service - Amavisd-new is an interface between MTA and content checkers.
   Loaded: loaded (/usr/lib/systemd/system/amavisd.service; disabled; vendor preset: disabled)
   Active: failed (Result: start-limit) since Fri 2020-08-07 09:10:08 UTC; 20min ago
     Docs: http://www.ijs.si/software/amavisd/#doc
  Process: 8582 ExecStart=/usr/sbin/amavisd -c /etc/amavisd/amavisd.conf (code=exited, status=255)

Aug 07 09:10:08 srv systemd[1]: Failed to start Amavisd-new is an interface between MTA and content checkers..
Aug 07 09:10:08 srv systemd[1]: Unit amavisd.service entered failed state.
Aug 07 09:10:08 srv systemd[1]: amavisd.service failed.
Aug 07 09:10:08 srv systemd[1]: amavisd.service holdoff time over, scheduling restart.
Aug 07 09:10:08 srv systemd[1]: Stopped Amavisd-new is an interface between MTA and content checkers..
Aug 07 09:10:08 srv systemd[1]: start request repeated too quickly for amavisd.service
Aug 07 09:10:08 srv systemd[1]: Failed to start Amavisd-new is an interface between MTA and content checkers..
Aug 07 09:10:08 srv systemd[1]: Unit amavisd.service entered failed state.
Aug 07 09:10:08 srv systemd[1]: amavisd.service failed.

OpenDKIM

opendkim.service - DomainKeys Identified Mail (DKIM) Milter
   Loaded: loaded (/usr/lib/systemd/system/opendkim.service; disabled; vendor preset: disabled)
   Active: failed (Result: timeout) since Fri 2020-08-07 09:10:37 UTC; 20min ago
     Docs: man:opendkim(
           man:opendkim.conf(5)
           man:opendkim-genkey(
           man:opendkim-genzone(
           man:opendkim-testadsp(
           man:opendkim-testkey
           http://www.opendkim.org/docs.html
  Process: 7718 ExecStart=/usr/sbin/opendkim $OPTIONS (code=exited, status=0/SUCCESS)

Aug 07 09:09:07 srv systemd[1]: Starting DomainKeys Identified Mail (DKIM) Milter...
Aug 07 09:09:07 srv systemd[1]: Can't open PID file /var/run/opendkim/opendkim.pid (yet?) after start: Too many levels of symbolic links
Aug 07 09:09:07 srv opendkim[7720]: OpenDKIM Filter v2.11.0 starting (args: -x /etc/opendkim.conf -P /var/run/opendkim/opendkim.pid)
Aug 07 09:10:37 srv systemd[1]: opendkim.service start operation timed out. Terminating.
Aug 07 09:10:37 srv systemd[1]: Failed to start DomainKeys Identified Mail (DKIM) Milter.
Aug 07 09:10:37 srv systemd[1]: Unit opendkim.service entered failed state.
Aug 07 09:10:37 srv systemd[1]: opendkim.service failed.


SpamAssassin

 spamassassin.service - Spamassassin daemon
   Loaded: loaded (/usr/lib/systemd/system/spamassassin.service; disabled; vendor preset: disabled)
   Active: activating (start) since Fri 2020-08-07 09:31:06 UTC; 19s ago
  Process: 23771 ExecStart=/usr/bin/spamd --pidfile /var/run/spamd.pid $SPAMDOPTIONS (code=exited, status=0/SUCCESS)
  Process: 23768 ExecStartPre=/sbin/portrelease spamd (code=exited, status=0/SUCCESS)
   CGroup: /system.slice/spamassassin.service
           ├─23773 /usr/bin/spamd --pidfile /var/run/spamd.pid -d -c -m5 -
           ├─23849 spamd chil
           └─23853 spamd chil

Aug 07 09:31:06 srv systemd[1]: Stopped Spamassassin daemon.
Aug 07 09:31:06 srv systemd[1]: Starting Spamassassin daemon...
Aug 07 09:31:07 srv spamd[23771]: logger: removing stderr method
Aug 07 09:31:13 srv spamd[23773]: spamd: server started on IO::Socket::IP [127.0.0.1]:783 (running version 3.4.0)
Aug 07 09:31:13 srv spamd[23773]: spamd: server pid: 23773
Aug 07 09:31:13 srv systemd[1]: Can't open PID file /var/run/spamd.pid (yet?) after start: Too many levels of symbolic links
Aug 07 09:31:13 srv spamd[23773]: spamd: server successfully spawned child process, pid 23849
Aug 07 09:31:13 srv spamd[23773]: spamd: server successfully spawned child process, pid 23853
Aug 07 09:31:13 srv spamd[23773]: prefork: child states: IS
Aug 07 09:31:13 srv spamd[23773]: prefork: child states: II

Install CentOS 6 and everything works perfectly

Hi, it seems like you have problems with your OS.
The errors you have are not CWP or default CentOS errors.