But - I have new news! I have started more or less from scratch - I made a live USB for Ubuntu have tried through Ubuntu and Heimdall. Got further, successfully installed e-recovery instead of TWRP, then sideloaded e/os/.
I have reached ‘Welcome to /e/OS’. I wonder if this is worth suggesting in the instructions if you don’t have Linux - it was much more straightforward.
Thank you. This made it very easy to install Heimdall on Windows. The fourth point in your link is also very important here: For Windows users only: install UsbDk. I almost overlooked that one.
With this help, I was able to install the recovery build eos 3.1.1-A15 for the Galaxy s10 without any problems via Windows.
The subsequent installation of /e/ OS then proceeded without this error message : “The current recovery does not seem to support dynamic partitions, …”
However, what did not work previously was installation using the Odin and twrp method - neither with A15 nor with A14.