[Poker Club Management] Management. Poker unions. Platforms

Hello everyone I'm the owner of a small poker club. Previously, we only played offline. My players said they want to play online, it's more convenient for them. When I registered my club on one platform, I was approached by several poker unions with an offer to join their league. Tell me, does anyone know why poker leagues are needed? What advantages do they provide? I will be grateful for the answers!