Hello!
https://www.catan.com/game/catan-universe
Usernames: schwink, emshl
We have tried the Steam Mac version and the iPad version and both work well.
It's "free to play" with a number of restrictions:
The store link is the bag of gold button in the top right corner. To buy stuff, you have to buy "Catan Gold" then exchange that for the expansion.
To add friends, click player button in top left corner, then "Friends". To host a game, click the leftmost button in the bottom row (selecting base game) and then "Custom Match", then add people.
Usernames: schwink, emshl
https://blokee.mattle.online/welcome
Usernames: schwink, emshl
Place where you can buy games for Mac and Windows. Also has matchmaking functionality for some games I guess.
Usernames: smschwink, emshl2
Preferred option (we have a Portal)