Ok, this is REALLY weird. It just worked fine TODAY, but from the second time it stopped working and started producing this error. Complete re-install of Workstation Pro didn't do any help, and I even restored Windows from a System Restore Point from a few days ago, and it still didn't help. I also uninstalled all software that I installed within the span of the last few days. Apparently, there's some broken registry value that appeared after the first successful use of this tool. I'm out of ideas.
I examined a Process Monitor log and found out that this tool always checks for the file openssl.cnf both in the Workstation's own folder and in a non-existent folder VMware\SSL. Also it tries to access the file libssl-3.dll, but gets a warning "This file is read only". I'm no expert, so I don't know what to do with all of this information. By the way, if I create a dummy file openssl.cnf in one of the above mentioned directories, the tool doesn't produce any errors anymore, but it doesn't do anything and just plain exits to command prompt without any messages. I think it needs the correctly structured file openssl.cnf, but I have no idea what I should put in there. And besides, this file doesn't appear when VMWare is freshly installed anyway.