Were are running 9.5 SP1 and had the exact same error as JDarrah in the HIIClient.Log
Found out, that our assigned driver package was stored in the wrong share eg. \\server\software-package-share\. all our software-packages are normally stored there. it was a batch-package. Once we copied it to the configurated driver-repository-share and adjusted the batch-package, the driver-package was installed.
My conclusion: The hiiclient.exe found that the name of the assigned driver-package in provisioning in "system configuration", but could not find the original files (even they were correctly configured in the software-package), because hiiclient is only searching downloading files in the configured driver-repository-share (unc or http). So you have to store driver-packages only in the driver repository.
Can someone confirm this?