2 things you can try:
1. Delete all leftovers of cRPG. Can be found in your Warband main directory under 'modules', and in your 'My Documents' folder, and in your appdata folder.
In order to get to said folder, press Win+R.
The 'run-prompt' should pop up. Type in %appdata%. Hit enter and find your Warband folder. In there should be some cRPG stuff.
Once you have deleted everything redownload the launcher, start it as an admin and try to install cRPG.
2.If that does not work, do the same steps again, but additionally uninstall Warband, and delete everything Warband related.
Redownload Warband
Launch it once
Start the cRPG Launcher and try to download it
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Will try to think of more possible solutions