The issue is I am not seeing the fork button at the projects level, just the repo level, but according to your documentation I should be able to. I am logged in as an admin and have admin, write, and read checked as per the default. Am I missing something? Without this ability, we might not be able to look at your product as an optionin our SCS search.
You can create a fork for any project or repository that you can see in Stash (that is, for which you have 'read' permission).