Hello, welcome back to OSM and forums.
Yes the game has changed quite a lot. Now all you need to create a league is boss coins and each league has its specified Amount of coins one has to pay depending on how many teams are on the league.
To create a league just select the slot you want to use and on the league selection page you'll find the option to create your own league afterwhich you click on the advanced tool and decide which feature to enable or disable (take care of the warning though), Then confirm.
Hope this helps?