Once you have gained access to the Clubs side adventure, you will begin to notice that Class action bubbles occasionally are coloured differently from the usual blue outlined bubbles. These options offer Club XP.
This is the main method of gathering Club XP. By using your Energy to gather more club XP you can increase your preferred Club level or open additional Clubs you have not yet opened.
Club XP may also be offered as rewards for performing well in your classes, hangouts, or during certain events as prizing.
Please note, only the study sessions/repeatable classes are assigned a fixed Club. New lessons from main story progression will have experience split between Club types.