If you are seeing this message when you attempt to login with your Bria Stretto Client. This indicates that your Stretto user has not been configured properly.
Please contact your Stretto administrator to have this resolved. They should take a look at the profile assigned to your user and make sure that in the "Template Mapping" section at the top there is a template assigned to the platform you are trying to use.
More detailed information about how this all goes together can be found in our Stretto admin guide in section 3.3.1, step B: Create Profile-Template Mappings.