When trying to import a User Certificate from Broadcom Support Online from https://eapi.broadcom.com/receiveorder/getSignedCert
It's possible to get the following messages:
<faultstring>Backend Service not responding.</faultstring>
<description>The server had a general processing error.</description>
Or if you get the messages:
Release : 15.0
Component : RECEIVE ORDER
The email address/Broadcom support userid should be connected to a siteid/company id with entitlements before getting access to the certificates.
Another possibility could be that a previous attempt failed and there is still some older data cached in the internet browser...Clear the cash of the browser and enter the url again. It should prompt you for credentials again and this would be successful.