Coudl it be that your repository is locked by a server task or that you are low on disk space ?
I don't think that problem with disk space (28 Gb free) and Master Repository because I have installed extensions for EEPC 7.0.2 without any issues.
I have 480.023 running on my 5 servers, don't remember any issue duing the install. Does this directory exist already ?
C:\Program Files\McAfee\ePolicy Orchestrator\Server\Extensions\installed\msa_help\480.022
I have finally installed this extension when I run ePO Console from server.