This Unreal 5.3 Gameplay Ability System video is about Saving and Loading Mission Data.
We start by creating the Mission Data Save Game Blueprint and add the Completed Missions Name Array to it. Next we create Load and Save functions in the GameInstance Blueprint, which are called from Event Init and Complete Missions. The Load Mission Data function will Load Game from Slot with a unique Slot Name and User Index combo, then cast that to our new Mission Data Save Game Blueprint and set the loaded Completed Missions to the Game Instance. The Save Mission Data function will Create Save Game Object of our new Mission Data Save Game Blueprint and set it’s Completed Missions from the Game Instance version and then Save Game to Slot with the same unique Slot Name.
https://dev.epicgames.com/community/learning/tutorials/7Jam/unreal-engine-30-saving-and-loading-mission-data-let-s-make-a-top-down-shooter