For what it’s worth, I built the machine this weekend. I built it in the living room of my apartment with minimal hand tools. The instructions are super clear and all the parts go together nicely. At no point during the build I felt there was a lack of information.
Also, I see you are looking at Stainless tubing. Unless you already have a plan, you should try and get it pre-cut to the length you are looking for. Pay the extra few dollars as it is hard to work with. Bonus points if you can get them to drill the holes you need.