Hi,
Currently, the setup script for Windows does not support installation in a directory whose path contains spaces. Please change line 41 of first-setup.bat from
mtxrun --script ./bin/mtx-update.lua --update --force --make --engine=all --context=beta --texroot=%OWNPATH%tex %*
to
mtxrun --script ./bin/mtx-update.lua --update --force --make --engine=all --context=beta --texroot="%OWNPATH%tex" %*
Then everything should be fine.
Thanks,
Christoph