Debian 10 php7.x not working

I have 3 problems to resolve:
1st: have installed 4 php verisons 7.1 - 7.4
I put (in public_html) index.php (phpinfo) file. When I open in browser I get possibility to download it. php not working!
2nd: I create one test email account, but I don’t get any emails?
3rd: I have installed ProFTPd version 1.36, but it can’t start!
any help with it?
Best regards,

Hi, Goran.

Have you tried re-running Re-Check Configuration from Virtualmin/System Settings, after installing new PHP versions?