Firstly, accessing the account this way is VERY BAD. This allows for bandwidth stealing. Set the domain up, point it, wait, then try accessing it.
If you're bound and determined to ignore security practices, you can turn on mod_userdir by going to whm -> security -> mod_userdir tweak, and unchecking it. Or, you can just allow that specific user through.
Note that enabling mod_userdir will break PCI compliance, so you best not be storing credit card info on the server.
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