Tutorial/Helper for Link to an iOS or an Android device

What is Link to an iOS device?
Can I transfer my entire progress from Android to iOS?
How does it work?
Is there a tutorial/helper for that?

Thank you

Alright, now I need help.
I need to change my phone and this could be it.
I don’t want to start another account.
How do I do it?

I have the same problem. Someone can help me?