Issues Installing skylendar program on zorin linux

Hi, I am attempting to install the skylendar software on my linux zorin system from skylendar download | SourceForge.net. But i have tried everything with no success.I just don’t have sufficient technical understanding to follow the instructions, or perhaps i’m doing something wrong or there’s something i’ve overlooked…i simply don’t know.

So, i downloaded the “tar.xz” file no problem. i unpacked it. But everything i try from this point onwards fails. Some of the commands in the instructions don’t work. Or my system doesn’t seem to understand them. I know there must be a way of doing it, but i’m stuck.

Life is too short to spend any more time trying to figure this out myself. So if there is anyone who feels able to help i would be extremely grateful for your assistance