I have a Friend who has bought this game via steam, and is nearing the end of his free 30 days.

But he cannot seem to find a way to add a subscription via his sqare enix/mog station account.

He is being told be MUST run his subscription via his steam wallet.
Is this something he will have to deal with? because he is not happy about it as it was not something that was openly told when he initially bought the game.

Is there a way for him to have his sub run normally?
If there is a way to have his sub via SE/MS please let me know.