Group chat app for Android and iOS

I need to create a chat app with a single group chat where members will be able to chat, send audio notes, imgs and videos.

I need:
- Registration/Login page
- Homepage with a preview of the chat. With the number of unread messages
- Page of the group chat. (You will see the first unread message since the last time you closed the app)

Functionalities:
- Registration/Login for only some authorized emails
- Logged users will be able to send text messages, record audios, send pictures or videos.
- Answer to someone else's message

- Push notifications and the settings to disable them
- Ability to assign the role of moderator to certain users from firebase.

A moderator can:
- Silence a user for x hours.
- Activate the slow chat mode. (e.g. an user will only be able to send a new message each 10/30 seconds or 1/5 minutes)
- Flag a user for ban