Hey!
If you're using the most recent version, v1.4.5, you're going to have to keep the "multi material UI" bool under the "Appearance" tab unchecked. It doesn't cause a crash on Mac, but causes a nasty crash on Windows, unfortunately. The bool was left in for when Unity eventually fixes the bug, or gets back to me on what else to do to prevent the crash.
For now, I highly recommend not using Unity UI, and just using the standard text mesh, which is fully-featured.
I have an "Anchor to Screen" script that replaces the screen-anchoring feature of Unity UI that I've been meaning to release, so I can give you an early version of the code if you want to try it out!
I also recently picked up a Windows PC, so I'll be trying again to solve this bug in the near future!
(Oh oops, didn't realize this was a reply to the thread at first, didn't mean to explain that all again)