Hi, Adedayo Ali
Sorry for this frustration. Since GroupMe says “PIN verified,” I wouldn’t keep requesting new codes or resetting the password. The next thing to test is whether something on the phone is stopping the sign-in from completing.
Try switching from Wi-Fi to cellular data for one sign-in attempt. If you use a VPN, ad blocker, or parental-control app, temporarily pause it for the test and turn it back on afterward. One GroupMe user confirmed that a parental-control app was the cause of their phone-only login problem.
If you’re on Android, you can also open Settings > Apps > GroupMe > Storage and choose Clear cache, not Clear data, before trying again. The menu wording may vary by phone.