Update: problem solved (I think!)
I erased my Wine installation completely and did a clean install, but this time using dotnet 4.7.2. Everything else was the same as my instructions in Installing Scrivener 3.1.1 on Linux (Wine 7.0) without problems.
Although I know very little about Wine, this suggests that the problem was simply connecting with Paddle for the 64 bit version of Scrivener. It might well be that with dotnet 4.6.2 the 32 bit version of Scrivener can be activated. With dotnet 4.7.2 there are no problems with activating the 64-bit version.
Once again I hope this helps those wanting to have a problem free installation of Scrivener on Linux.