Current link/connection potions between android and apple products 2021?

on my phone I get the options to: "sign into google play" or "link a device", when I press "link a device" it tells me to choose a service, and only facebook is showing.
I have tried the "sign into google play" aswell, but that is not an option on the ipad.

the problem is that the game wont let my ipad connect my account to facebook. When I try to login it just resets the facebook login page and tells me to login again.