Like we said before, rankade is not a social network.
Rankade is designed to manage your group, a group of real people playing real matches.
It makes no sense to add a user to your group if they don't play with you and the others.
You just don't 'ask someone to friend you'.
It's easy to join a group: just play with that group's members.
And if you start playing with a group that doesn't use rankade, you can create a new group for your matches with them.