Cannot update MacBook Pro mid 2012 iTunes 12.4.3 - Which then prevents me from updating from Mountain Lion to the newest OS

I just rebuilt a MacBook Pro Mid 2012 with a new SSD and 16GB ram, it was inexpensive and a great way to get it running as good as my other MacBook Air 2017.

All that said, I did not want to clone the old HDD and I decided to just rebuild the OS from scratch. I was able to get Mountain Lion OS on there and able to do most of the firmware and security updates.

All that is left is the iTunes 12.4.3 update but it keeps giving me the error -102. I tried downloading other iTunes updates after that (like 12.6) but there is no link or the icon for the link just says "Download Icon" in unclickable words. For 12.8 iTunes it requires a higher version of Mac OS but I don't think I can update the OS without these updates.