Twindad
I get the feeling a bit frustrated with this, but what ErnestThornhill was getting at, in my opinion, is that its hard to get pointed help if you were unable to grab an error code that appeared along with "unexpected error".
There should have been a string of text following that. That can help the forum say " hey try this ". But without it then it will be questions of; are you using a recommended OS on your computer and recommended browser? Along with is there enough memory on your computer.
Those are things I have heard produce unexpected errors. I believe most recently was a user trying to install with Vivaldi browser. Just a heads up if you're using Brave, make sure shields are off.
Hopefully someone else can offer more specific guidance than I've offered.