When you buy the license along with support, part of the order fulfillment should be to add the designated customer's cisco.com account to have entitlement for the download.
Like @balaji.bandi mentioned, you should ask your Cisco SE or partner sales rep to address the issue for you. Don't just have them give you the file but rather insist they address the root cause (lack of entitlement) so that you get ongoing access for upgrades and support.
