It seems to run fine as follow. The same call answer correctly. Thank to Massimo Giordani who make some try.
If you like do-it-yourself, you may put an additional case in the GetNotesTempDirectory, adding Windows/64 like this:
Select Case session.Platform
Case "Linux"
s% = linux_OSGetSystemTempDirectory(d)
Case "Macintosh"
s% = mac_OSGetSystemTempDirectory(d)
Case "Windows/32"
s% = w32_OSGetSystemTempDirectory(d)
Case "Windows/64"
s% = w32_OSGetSystemTempDirectory(d)
Case Else
Error ERR_UNSUPPORTED_PLATFORM, "In GetNotesTempDirectory, platform not supported: " & session.Platform
End Select