@PiotrBujakowski
Because there is no Ubuntu Touch port for your device.
https://devices.ubuntu-touch.io/

And Ubuntu Touch is not the same as "Linux Ubuntu" for desktop, you can't install it the same way, like I said, it need to be ported by someone, maybe you if you have skill for, but it's a long and hard job to be done.
https://forums.ubports.com/topic/2068/halium-first-steps