Hey there, we are not 100% sure why unity asks for that permission. It might have something to do with providing us with general player stats (like in what country do we have the most players). We do not manually track anything whatsoever. You can opt out of the unity stats aswell in the options, if you don't want that :)
As for the installation, I'm not sure. Never heard of that issue :/ Maybe there's like a previous installation and that's being an issue? Maybe try searching in google, it sounds like more of a general problem :)