It’s good to give everyone in the family their own OS level account. Helps keep things nice and separate, reduce risk of the kids trashing your files, and for Steam, it avoids having to enter your password and Steam guard code every time you what to change who is playing.
Unfortunately, Steam is a little finicky on macOS, because games are installed
in each user’s home directory by default, under ~/Library/Application Support/Steam. This means that either you can’t see other users games at all,
even with family sharing enabled, or you have to download the same game multiple
times on the same computer, wasting disk space.
Instead, you can create a single default library folder location for Steam to put all of your families games.
First, create a new directory to hold your steam games:
$ sudo mkdir /Steam
$ sudo chmod a+rwx /Steam
Then, start Steam and in the preferences, go to Downloads. Click on “Steam
Library Folders” and then click “Add Library Folder”. Add the newly created
/Steam directory. Right click on it and make it the default. Download games.
If you already have games downloaded, you can right click on them, go to the
local files tab, then click the “MOVE INSTALL FOLDER” button. Make sure the
/Steam directory is selected, then click move.
Once you got some stuff in the /Steam directory, make sure everyone can read it.
$ sudo chmod -R a+rwx /Steam
Now you should be able to log into Steam on the other accounts, and go through the same process to set up the new default library folder.
Happy sharing!