So I'm follow your instructions verbatim, but when running the ConfigMgrSetup, it bombs out. This is in the log:
INFO: Verifying hash for file 'C:\Source\SCCMPrereqs\msrdcoob_amd64.exe' $$<Configuration Manager Setup><11-15-2019 11:09:15.943+300><thread=4688 (0x1250)>
WARNING: File hash mismatch for C:\Source\SCCMPrereqs\msrdcoob_amd64.exe $$<Configuration Manager Setup><11-15-2019 11:09:16.075+300><thread=4688 (0x1250)>
INFO: Downloaded file 'C:\Source\SCCMPrereqs\msrdcoob_amd64.exe' is not valid $$<Configuration Manager Setup><11-15-2019 11:09:16.095+300><thread=4688 (0x1250)>
ERROR: Failed to download required file $$<Configuration Manager Setup><11-15-2019 11:09:16.116+300><thread=4688 (0x1250)>
Is there a way to get around it?