there was mod response in (one of many !) similar thread.

In order for referal link to work you need few things:

- new install (there was never raid installed on friends device - no matter account registered for it) before clicking your link

- friend have no raid on his plarium account (other deviece - same account) before clicking your link

- must be done on real device - bluestacks or other emulator is big NO

- allow targetted ads and agree to have absolutely no privacy (both ends of the deal if I remember right).

They will then be able to link new install account with the one generating link.

fail any of those and it just won't register, AKA you have lured new player (possible payer) for nothing ...