How to add invitation code or share to unlock without being rejected?

I would like to add two functionalities and I wonder if they are aligned with the IOS guidelines.

1. Invitation code.

#1_Reference=Jumpspeak. On sign-up users are asked to add the invitation code. If you don't have the code, you can't access. https://apps.apple.com/us/app/jumpspeak/id1514709368 #2_Reference=Clubhouse. You can only access if someone invited you with their phone number. https://apps.apple.com/us/app/clubhouse/id1503133294

How can I add invitation first users to the app? My plan is to ask an invitation code before sign-up. Is it possible? How can I make it work.

1. Share to unlock

#Reference_1: CoinMaster. They ask you to share with your friends to unlock new spins and be able to continue playing. https://apps.apple.com/us/app/coin-master/id406889139

How can I add this functionality to my app? My plan is to ask users to share to unlock new lessons. Is it possible? How Can I make it possible?