Family Sharing and Minecraft

I purchased Minecraft on my account, but I'm also the "family organizer" -- it is my 12yo who actually wants to play the game, so I'm trying to figure out how to give him access to it without logging him in as me or buying it a second time.

Not sure if it makes a difference but we've all got Ubuntu laptops. Not xboxes.

He's been able to play fine, but he has to be signed in as me.

:)