I know this has been a common post. I have searched through the forums and found people having the same issue, and it has been unresolved. I am in a different situation. I am working at home, my laptop will not load muse beta 7, but my desktop at home will. I turned my firewall off and tried with it disabled, but that did not work. I am using the same internet connection as my desktop which is able to use muse beta 7.
If you are seeing the first screen 'Unknown Error', could you please check to see if the file /User/<user>/Application Support/Adobe/OOBE/opm.db (Mac) or \Users\<username>\AppData\Local\Adobe\OOBE\opm.db (Win) exists. If it does not, could you please email me the log file /Users/<user>/Logs/PDApp.log (Mac) or %temp%/PDApp.log (Win) to firstname.lastname@example.org.