Is your profile showing a pending message? In this case, you need to enter with your profile password and confirm the security check on Instagram.
Step by step
1. Login on Instagram Web;
2. Access your Profile Settings in Postgrain;
3. Put your password;
4. Choose one of the options: Application (It Was Me) or Code sent by Email/SMS, then confirm the security check according to the chosen method;
5. Confirm 'Solved' on Postgrain.
Always login to Instagram Web before entering your profile password on Postgrain.
Postgrain doesn't support two-factor authentication, so you will need to disable it.
If the profile pending persists, remove the profile and try adding it again. If the problem still persists, please let us know.