Okay, you say you are using UGS which is a stand alone G-code sender program but you are showing a screen shot of Easel which is a different web based program that is a CAD CAM and Sender all in one.
to run the web based program Easel you will need to install a driver called Easel Local. this will install the files needed to connect the program Easel to the X-Carve. they have made drivers that you can install for windows, Linux (X86) and MAC. If you want to install Easel Local on a different architecture like ARM or ARM64 (raspberry pi) you will need to compile (make) you own. how to do this is outlined in the post by @SamyKamkar in post Easel Local for Linux? - #17 by SamyKamkar
If you want to use UGS to send your G-Code to the X-Carve then you need to use a CAD CAM program to generate your G-Code and save that file and then run the UGS program to send it to the machine. UGS is a Java based program and you can use it without the internet. As far as which one I use, I have been using version 1.0.9, the only issue with the Pi is that I can not get the visualizer tab to show tool paths but I do not care as I see them in the program I use for generating the G-Code file.