I think the way the bundle is currently implemented by Mojang is not sufficient and we can improve it!

The plugin modifies the game logic so that you can store several potions or enchantment books in one bundle.
Such “overflowing” pouches may contain either only potions or only books. For example up to 8 potions in one bag.

The plugin does not add a craft of bundle, you need to take care of this yourself (on my personal server you can buy them in the admin shop).

Unfortunately, the mechanic of adding items to the bundles does not work correctly in creative mode at the moment (use survival or adventure). Hope this will be fixed in 1.20+.