Only use a usb 2.0 port on pc and usb 2.0 cable during the installation. I made this mistake when I installed my pixel 3A. The installer only works with usb 2.0 not usb 3.x. Tick both Wipe userdata and Bootstrap.
Terminal is installed by default on ubports Ubuntu Touch, but maybe as it's "unused" he's still on a canonical one, where it was not.
Maybe first he should update to last ubports UT update ^^