First, off, warning... I have never installed UB Touch. Also, I'm not clear enough on what you have already done to know if I'm just suggesting something you have already tried.
Looking at this page (I'm assuming you have the Pro1x):
https://devices.ubuntu-touch.io/device/pro1x/
It appears to me you download an installer (links at the bottom of the page) to your computer and it downloads and installs UB Touch (presumably OTA-5, since that is listed as the stable version on that page).
Again, I may be making way too many assumptions, but if I were interested in UB Touch, th