I've purchased a virtual server, where I'm given of a non-root sudo-enabled user.

Actually I do need to create an FTP account that's not that sudo-able account, so I created a no-login account just for that purpose. I've set up VSFTPd correctly, also enabling the "userlist" feature, to specify which user are permitted to use FTP.

Then I created an empty directory under my sudo-able account, and I gave ownership permissions to the second account, so to make it more easy to understand, let's say the main account (the one I do use to manage my VPS) is called ubuntu and the FTP-user is named ftpuser, I created a directory /home/ubuntu/mywebsite giving the ownership to ftpuser:ftpuser. Then I uploaded a worpdress website, whose default permissions are 755 and 644. The issue is that Apache is not given of any privilege to run the website.

How can I make the website run properly, and which is the most secure?

Should I run that virtualhost with another user (if it's possible)? Should I force the FTP user to use the www-data group (if that's possible) and run with permissions like 775 and 664?

How can I solve this issue? Any help is appreciated, I'd like to run it using the default permissions, so any update won't break up anything (because of permissions reset).