So this appears to be a bug with Start11. I went into the registry and removed any references to Steam and Valve, uninstalled Start11 again, then removed any reference to Startdock in the registry. Install the same installer again from the trial page and it asked me for my product key.
I followed the steps and run the purge all which uninstalled Start11, then install Start11_setup.exe which I got from the trial link but it also has the Failed to Authenticate message. I did previously have Steam installed on this computer, but I no longer do.
I recently upgraded from Start10 to Start11 even though I hadn't upgraded my Windows yet. Today I went ahead and upgraded to Windows 11, and installed Start11 from the link that was in my upgrade email. When I purchased Start8, Start10 Upgrade, and Start11 Upgrade I did it through the website each time. After running the Start11 install it says "Failed to authenticate Start11 with Steam. Please ensure that Steam is logged in with a working internet connection and try a