Facebook "This page does not have permission to install the custom tab" error
Facebook changed its API and is no longer allowing Pages with fewer than 2k Likes to install custom tabs. If your Facebook Page currently has less than 2,000 followers, you may not be able to add ...
Yes, if you are trying to add a 3rd-party iframe tab to your Facebook Page and you haven't previously authorized the 3rd-party developer, you will need to get 2,000 ...