If your account is
set to private, anyone who wants to see your photos or videos will have to send you a follower request.
To approve or deny a follower request on Instagram:

Instagram app for Android and iPhone:
- Tap
at the top to see Follow requests. - Tap Confirm to approve a request. Tap Delete to deny a request.
If you accidentally deny a follow request, you can ask the person to request to follow you again.