Anuke will require some server(s) for a friend system and a server is NOT FREE. That's why the steam version requires payment. Steam has the servers for easy multiplayer and a friend system.
you can make a request on github. you can get servers for free. but low spec and have to renew after some hours. the fact that the game will cost money wont bother me. in fact he deserves the money. more than you can think.
PS: there is a trello page: https://trello.com/b/aE2tcUwF/mindustry-trello
and join the discord for more info and dev preview
and the game will remain free on itch (i think)