Simply follow the official instruction https://forum.raspiaudio.com/t/ultra-installation-guide/21
Even though the official instruction is very complete and accurate, as a perfect newbie, after having installed everything, I still struggled with some aspects.
As I made some doubtful experimentation with my ~/.asoundrc file (which I don't advice),
somehow it contained wrong entries.
I finally replaced my ~/.asoundrc by the one present in the instruction's repository :
https://github.com/RASPIAUDIO/WM8960-Audio-HAT/blob/master/asound.conf
Maybe a simple remove would have worked...
A lot of preset are provided in the instruction repository but not the one I wanted.
A little diff script made me build a preset using full onboard capabilties : speakers and microphones.
Here is the result: preset_onboard_speakers_and_microphones
If RASPIAUDIO Ultra+ drivers has been installed correctly. We should see several possible configurations in pavucontrol :
On my side, I had to choose the selected one in blue otherwise mic and speaker was blocking each other