how to create a subfolder with different password and user?

I need to create a subfolder from which a few friends can download some of my files, without them having access to my main folder.

I am using SmartFTP and I created a subfolder meant for this, but now I want to secure it with a different password and a different username than those for my main directory.

I tried a few commands (adduser) but I always get the error: SITE ADDUSER not understood.

How can I manage this?
Thank you very much!

Hi, the server must allow that, and it's very likely it don't, you must speak with your hosting to make a new account for that or you must add it ussing the ftp server and not SmartFTP.

Hi, the server must allow that, and it's very likely it don't, you must speak with your hosting to make a new account for that or you must add it ussing the ftp server and not SmartFTP.

I'll try it that way, thanks!