If your profile is private, your friend request will be ignored unless I know you.
If you send me an unsolicited friend request, I will ignore it unless I know you.

Being a friend of a friend doesn't count as knowing you.
Commenting on a workshop item asking to add me doesn't count as knowing you (and is unsolicited).

If your purpose of friending me was to ask for permission to modify or edit something I uploaded, go for it as long as you credit me AND do not profit from my work.