itch.io

No need to repurchase! Just re-download the project from the store page and you should now find a (Battle Version) project in the folder. 

Battles work a little weirdly in RPG Maker, and Common Events are treated as separate things, so trying to run things like Parallel Processes don't generally work. I've made a version where the QTB is condensed into one Common Event that can be called during battle via skills, items, battle events, etc. that should now work.