As much as I fiddled with it and it’s source it looks like this plugin completely ignores Gameplay Ability System that’s built-in unreal engine.
It’s a separate system.
What’s different is how abilities are executed and probably most notable difference and a nice addition overall is the ability timeline that you can setup tasks on, deciding over which part of ability (time wise) which tasks do their job.
You could somewhat create abilities at runtime but you would need c++ knowledge to expand on this plugin’s system for that.
I haven’t used passives yet, but I assume 1 AbilityComponent can have multiple passives at once but only 1 active ability at a time