its likely because you are using cpanel to do this and its being a stickler
for permissions and quota's, have you made sure the account you are running
it under has a large enough quota > approx 175GB?
also have you made sure you have amended the scripts so that it downloads
into appropriate paths?
for anonymous ftp on cpanel, you have to have files in the public_ftp folder
and have anonymous ftp enabled within whm, however public_ftp wont serve out
on http, so you will probably need to symlink your public_html folder to
public_ftp for that to work or duplicate the whole mirror which would be a
waste of resources and hd space
i cant say i would recommend mirroring from a cpanel server but its not
impossible