HDD should be formatted APFS instead macOS Extended (Journaled) as writen in tutorial.
I’m installing fresh right now and noticed that too, but the initial installation completed without error.
I didn’t realize the CATALINA volume was HFS until the 2nd Clover boot.
I just chose it to complete installation and it’s almost done. Let’s see if it’s still HFS or if it was converted by the installer on the 2nd pass...
...and it looks like the 2nd pass of the installer CONVERTED the volume to APFS!
So, it is permissible to format a fresh (empty) Catalina target volume as HFS, it will be converted to APFS by the installer. I would assume this process erases the data on a HFS volume.