If you get an error from the second command in step 2, add “–fix-missing”, like this: sudo apt install build-essential libtbb-dev libtiff5 x11-apps git --fix-missing
It works well with Ubuntu 18.04; I haven’t tried with 20.04 but should work --I tried the compiled version for 18.04 on a ‘real’ Unbuntu 20.04 and it works.