Check if you are able to login to the model using Sparx Enterprise Architect. If no, the credentials are invalid. If yes, you must be using the default credentials when you enabled Security in EA, which is admin and password.
You need to use the Change Password option once to resolve the issue. Change the password in EA and use the same in Prolaborate. You can even change the password to password. Once you go back to Prolaborate and refresh the Repositories page, the status will change to Active.