I think I saw the same thing about running an install program and agreeing to some liscense agreement. I hope that is for the admins and such as I think I'll pass on installing software on my computer.
What you saw was for me. All of that was for the server side. I was not expecting anyone to be on during the upgrade window. Because the server is hosted by someone else I did not have the luxury of migrating using a second virtual server. If I had that as a possibility no maintenance window would be required.
The new forum will look much like the current one only with way more features. The only requirements will be that you have a modern web browser and an internet connection. No special software, licensing or downloads.