[Solved] I just purchased and doesn't work
Thank you for your purchase.
wpForo has a built-in spam control system. It controls newly registered users and allows to attach a file and attach link when the user has X number of approved posts. Please manage this setting in Dashboard > Forums > Tools > Antispam > New Registered user section.
BTW you can set this option 0 if you want to allow just registered users to attach a file.
Thank you that did the trick