The same thing happened to me. And I was trying to sign up/log in to Instagram through Facebook. Why am I allowed to log in to and use my Facebook account but n

The same thing happened to me. And I was trying to sign up/log in to Instagram through Facebook. Why am I allowed to log in to and use my Facebook account but not allowed to sign up for Instagram using my Facebook account? If they thought I was a bot or fraudulent user then surely they'd have the same concern about my Facebook account? It doesn't make any sense.