Error 102 trying to update iTunes after restore

hi! Really need help.

so I had macOS Catalina on my very old Mac air and was having somo problems the sort, it seemed I was using more a windows PC than a Mac. I decided to do a restore, I erased my disk, and started from scratch and now my Mac is running on macOS mountain lion 10.8.3 with my Catalina Backup (tried with no backup, same issues). I need to upgrade to Mojave or sierra at least as this macOS kitty is really old and nothing works, but turns to be imposible as I continusly get error 102 when I try to update iTunes 12.4.3. I ve tried downloading macOS dmg for High Sierra it didn’t work, my Mac made my trashed before running it (also happend with chrome dmg and I keep getting “safari can’t open page” because ir wasn’t established a secure connection on pages as suppor.apple.com)

I’ve already tried the web’s solutions for error 102, the login stuff, the erase file from cache, no file for iTunes on library preferences so I did not do that, tried to delete iTunes from appllications to “uninstall “ it.

can someone please help? :)