Thanks for the suggestion, I did find the log files in a folder under AppData...
C:\Users\UserName\AppData\Local\Temp\AffinitySetup\419bcc15-e67e-11e8-87ad-6045cb9fb899
Also, there were entries in the Event Log, which indicated as suggested yesterday, that the installer is corrupted. I downloaded the installer twice, they both do the same thing. Both were "affinity-publisher-beta-1.7.0.162.exe" with the version number attached. Neither behave differently, i.e. both fail to install the same way.
The first error in the Event Log was:
Product: Affinity Publisher Public Beta -- Error 1335. The cabinet file 'Main.cab' required for this installation is corrupt and cannot be used. This could indicate a network error, an error reading from the CD-ROM, or a problem with this package.
I can post the SetupUi.log file, but I doubt it will tell you much more, other than the exact config of my machine.
Any further thoughts are appreciated.