I had the same problem. I made a mistake and posted it on another forum, but I was able to solve it and I’ll share how I did it.
I still had the installer for the previous beta (2.9.9.10) in my Chrome download folder, so I installed it first. Without uninstalling the previous beta, I immediately tried installing the new version, 2.9.9.11, and it worked.
I hope the installation is successful as well.
For some reason you are using the update installer executable and not the full installer.
Running it after a full installer is not a problem. I would recommend downloading the full installer one more time from the source announcement thread.