I had to install 2019.3 on my machine, (Don't ask why, just go with it). I used the link on the archive page that will install it though Hub, for whatever reason, this failed. I went to reinstall it, but Unity Hub says that it's already installed. I had Unity hub delete the files, which it displayed an error that it couldn't. I clicked on the show in explorer link, and manually removed the files, and it still shows the install in the list, and the can not delete files message. I should add that after every change/attempt, I have right-clicked on the Unity Hub icon in the system tray and chosen quit Unity Hub. The failed install version still shows in the installed list, I still can't remove it from that list, or reinstall it. Also, Manual installations fail, as it opens Unity Hub, which then says that it's already installed. Help?