Thank you a.p.
When you say
only a guess, but did you already try to installation using the default VMware ESXi image?
could you please clarify what exactly you call the default image? Would this be version 6.0 without any updates or the latest 7.x available?
The directory for ESXi 6.0 U3 also contained a zip file (VMware-ESXi-6.0.0-Update3-9313334-HPE-preGen9-600.9.8.5.4-Sep2018-depot.zip) but I did not know what to do with that.
In the meantime I am going to try 5.5. U3 which is the other version claimed to be compatible.