If you've ever ordered followers and seen nothing arrive, this setting is the usual reason.
What it does
Instagram's Flag for review setting holds follows from accounts it considers suspicious so they don't appear immediately.
How to turn it off
- Open Instagram → your profile → ☰ menu.
- Go to Settings and privacy → Follow and invite friends.
- Turn off Flag for review.
(Menu names change slightly between app versions.)
Also check
- Your account is public.
- You haven't hit Instagram's limit on pending requests.
- You entered the right username.
Turn it back on after your follower order completes if you want.