FTP does not work

Since the beginning of the installation, FTP does not work properly.

I always have to select this option:

IMG: https://prnt.sc/rs5ikk

But now I'm having problems, because my customers are questioning, they want to make a secure connection.

I try to connect using the quick option and look at the error:

IMG: https://prnt.sc/rs5hrl

How to fix this?

I've done all the configuration processes that exist on the site.

IMG: https://prnt.sc/rrugv3

Thanks.

You don't say how the clients are trying to connect.
https://www.howtogeek.com/194740/what-is-the-difference-between-ftps-and-sftp/