How to reward user for inviting a friend

So i build an ecommerce app that will let the (user A) invite a friend to signup on my app and when (user b) signup using (user A) invite code (user A) will get a reward and his points will increase i hope it make sense. I’ve been looking for answers in 6 hours. i hope you can help me

One way to do it:
You will need to generate a URL for user B to use or share, this URL will contain a parameter in the URL with code or number or whatever that is for user B only and no one else.
On the signup page, you would have a condition workflow on the signup button to check if there is a parameter in the URL, if so, do a search for using that parameter content to look for the user that it belongs to, from here everything is linked, you can increase points or do whatever you want for user B.
it is pretty easy to do if you are familiar with Bubble.
Good luck