I tried again to install howdy and now I could install it but when I tried
sudo howdy add
I get an import error

I am attaching the screenshot

Thanks you very much and best regards

I was also having issues after installing Howdy yesterday on ZorinOS (Ubuntu 20.04) - got the "command not found".

Tried purging the app, cleaning/autoremoving apt, then finally re-installed successfully (where I saw it downloading Numpy packages), so I guess it was just a blip in my initial install process.

I'd say try the following, then see if you get a different error (cause it seems like some missing/improperly installed dependencies somewhere)

sudo apt purge howdy

sudo apt autoremove

sudo apt update

sudo apt install howdy

A spontaneous shutdown is new behavior for sure. The installer runs a c compile that can take quite a lot of power, maybe your power supply is not up to the task?

The second issue is a corrupted install, the steps from @ntfrueh will help there