From your screen shot, it does not look as if you are using Splunk Light. At the upper left corner, you should see a Splunk Light logo in orange. Is it possible you have an Enterprise trial or free license active?
Based on the error message, this does seem to be a matter of your role not having the necessary permissions to add data to the instance. Sorry if this is a basic question, but are you sure you are using Splunk Light? The screen shot appears to be Splunk Enterprise.