FIM Administration Portal - Unable to process your request

Recently, I posted a question asking on how to delete management agents;

https://social.technet.microsoft.com/Forums/en-US/96cc60ec-baab-4e0f-be3d-609518f4c042/unable-to-delete-management-agents?forum=ilm2

After a few days of trying to find the Administrator Account to log into the Administration Portal to attempt to follow the steps outlined in the above link, I find myself with a new issue.

1. I am trying to log into the FIM Admin Portal, which I assume the URL is: http://SERVERNAME/IndentityManagement, is this correct?

2. I get the following error message after using credentials;

Not really sure what has gone wrong here, nor how to resolve this issue.

Thanks in advance for all advice here.