You have to be Salesforce administrator to set up permissions to access DataGroomr.
1. Go to Salesforce Setup -> Manage Connected Apps and Edit DataGroomr
2. Make sure Permitted Users are set to "Admin approved users are pre-authorized" and click Save.
3. Return to the Manage Connected Apps and click on the DataGroomr app.
4. Click on Manage Profiles and select those profiles that you'd like to be able to see the app in Salesforce.