If you can’t follow people on Instagram, it’s likely a temporary action block from too many follows/unfollows. To fix it, wait 24–48 hours, log out and back in, update the app, and avoid repetitive actions. Once the block expires, you can follow again.
You might can’t follow people on Instagram because of temporary limits caused by too many follows in a short time, a recent app bug, or a restriction on your account. Try waiting a few hours, updating the app, or logging out and in again. If the problem continues, your account may be temporarily blocked from following more users.