Trouble installing Quake Injector

Just discovered this site and I’m trying to install QI. The readme.txt says to click a .bat file which doesn’t exist or to double click quakeinjector.jar. When I do this I get an error “C:\Quake\quakeinjector.jar Class not registered”. I also tried ‘java -jar quakeinjector.jar’ at the C:\ProgramData\Oracle\Java\javapath_target_88092812> prompt (it wouldn’t run anywhere else). This at least opened the app… almost. I get a pop-up that says “Downloading failed! Failed to fetch current database; using previously downloaded info.” I click OK and I get another pop-up that says “Database parsing failed! Database parsing failed! cannot download package database or read local cache”. I click OK and I get another pop-up that says “Quakepaths incorrect Quakepath isn’t set correctly. It needs to be set before trying to install (or play).” I can Open Engine Configuration or Cancel. I Open Engine Configuration. I get an Engine Configuration dialog box that asks for the following: Quake commandline options, Quake Directory, Quake Executable, Download Directory, Expansion packs installed: rogue; hipnotic. That’s as far as I get.

What am I doing wrong?