How do use the 4 app slots included with free?

It states on your website that 4 apps are include with the free plan. I'm using the free tier as a trial to see how Akaunting functions compared to QuickBooks Online, but so far I seem to be unable to add any apps (even the free ones).

Can you help me get the QuickBooks app installed (it goes to 100% and stalls there, never actually installing even after walking away from my computer for a bit)?

I'd also like to know how to go about using some of the 4 slots for other apps so I can see what Akaunting can do for me.

I read that QuickBooks app can only be used in the Cloud service.

https://akaunting.com/apps/quickbooks

From what I can see the Apps included in each plan are predetermined, you cannot pick and choose the apps you want. Can anyone confirm if this is the case?

If so, is there a list of which apps are included in each plan?