Just in case someone else runs across this. While on Chrome and attempting to launch the virtual lab it seemed to hang indefinitely. (In my case I had previously run another lab)
I was able to get it working by deleting a few cookies including the one for Dremio University and Cloudflare.
Right click lock in browser location bar and select cookies
Highlight cookie and click remove.
A simple page refresh seemed to work from this point for me.