Ubuntu 18.04.5: cannot load module for Intel Wifi adapter [duplicate]

I'm running an Acer notebook that comes with an Intel WiFi adapter. The included kernel does not support it natively, so I found some separate drivers which are installed via dkms. Unfortunately when calling

modprobe iwlwifi

an error

modprobe: ERROR: could not insert 'iwlwifi': Required key not available

is returned.

I already found a solution to disable scure boot via mokutil, but this does not work for me here - when I do this, loading of the kernel fails at grub boot level and I can't get into it at all.

So...how can I fix that, how can I get my 18.04.5 working with the Wi-Fi 6 AX200 chip?

Thanks!

UPDATE: to all the "I'm so clever in closing questions"-people: my question was NOT answered somewhere else. The solution you linked to suggested to disable secure boot - which doesn't works with newer BIOS versions. Disabling secure boot via MOK prevents Ubuntu from booting at all. So thanks for closing this question while not understanding what really is going on!