At point of first downloading the mega-app
When you first download a mega-app you will see a list of available toolkits. Tick all those you wish to download at that point.
From within a toolkit
Click on the burger menu (5 horizontal bars) in the top right corner.
This opens up a panel with a green cloud bottom right.
Click on the green cloud to see a list of available toolkits.
Select the toolkits you want to access.