At the moment it is possible to send someone a link to challenge another player lichess.org/?user=username#friend
This would help a lot to schedule a tournament, either round robbin or swiss, whatever, but overcoming the challenge to teach 65+ players to create a challenge themselves, to specific parameters stated by the tournament manager.
If it would be possible to add the time and colour and rated parameters, the manager can manually schedule these round robin tournaments himself, until such time that the developers can add more tournament types.
eg. lichess.org/?user=xK4LIBUR?time=15+15?Colour=white?variant=standard?type=rated#friend
maybe it is already possible, and I'm just not aware of it?
This was mentioned in another thread, but might get lost in that noise, and I believe it warrants a dedicated thread.
lichess.org/forum/lichess-feedback/round-robin-tournament?page=3#29
in other words, I can create the complete challenge for the player, and just send him a link to click.