Without telling you, Windows may have enabled OneDrive and your Maya installation may be not where the Carbon installer is expecting it.
It is currently not possible to specify a custom installation location with the Carbon Windows installer (we will fix this for V2).
But sometimes you may need to do a custom installation, for example if you are using OneDrive then Maya
has probably installed on OneDrive, which means here %USERPROFILE%\OneDrive\Documents\maya\
If you need to do a custom installation of Carbon then check out the info towards the end of the getting started document
here
Carbon-Cloth-For-Maya-Getting-Started
If you need help then please post a message on this forum. Txs
