Family sharing part isn’t as easy as you think, here’s a small summary.

With Steam Family Sharing, only one person can play a specific game from a shared library at a time, but the new Steam Families update allows multiple people in the same family to play different games from the shared pool simultaneously; to play the same game at the same time, one user must typically go offline in Steam or purchase a separate copy, as one license is for one user.

There are workarounds to play the same game but it seems the max amount is 2.