Can I add my own apps or games to CashTap to collect taps?
No, unfortunately, that is not possible.
I am receiving only one suggested app each time
This is how the app suggestions work at the moment. In the future there might be more apps suggested each time the button overheats or when you want to earn auto-tap time.
Do I have to download a new app every time? I do not have enough space on my device.
The overheated screen and auto-tap time screen are scrollable to the left and right. Your previously downloaded apps can be found there. So if you prefer to not download a new app, you can scroll away from the new offer and play one of the apps you previously installed instead. You can see all the apps that you installed via CashTap in the "Installed Games" at the top left corner menu.