The Archive.exe is missing. You can copy it from the 32bit version. This works for the modtools, hopefully for the worldbuilder as well.
Thank you! I will test this out tomorrow, fingers crossed!
The WORLDBUILDER also needs the BUGSPLAT.DLL file.
It is not obvious from the Worldbuilder error. You just get the ARCHIVE.EXE failed message.
I ran Jannes map extractor and it reported it needed BUGSPLAT.DLL.
Then the worldbuilder worked fine for me.