Make sure to only follow this guide if the automatic creation of an API-User keeps failing.
The quickest way to manually create a new API-User and check the API-role is as follows:
1. , 2. , 3. navigate to System -> Web Services -> SOAP/XML-RPC - Users,
4. click on Add New User,
5. Fill all fields under User Info and note down the User Name and API Key that you've chosen,
the Firstname, Lastname and Email are required but not used anywhere.
6. Switch to User Role and tick the Role named cobby,
7. Afterwards click Save User,
8. Then check if the user is now part of the API-Role "cobby":
navigate to System -> Web Services -> SOAP/XML-RPC - Roles,
9. Click on the role named cobby,
10. navigate to Role Resources and check that the resource cobby is checked,
11. navigate to Role Users, the User Name you have chosen in 5. should show up here,
12. save the role with a click on Save Role,
13. Navigate to System -> Configuration -> Services / cobby and select the new users name from User Name, then enter the password that you noted down in 5. under API-KEY.
14. Click on Save Config in the upper right corner.