When a user has access to a hosted feature layer in ArcGIS Online, and they do not own the layer, nor does the layer have "Allow others to export to different formats" enabled, they cannot use Map Viewer's Extract Data. If they attempt to do so, the job will fail with "AO_100026: Extract Data failed"; however, that message is not unique to this set of circumstances and is returned for a number of different scenarios.
It would helpful if a user's ability to export data was verified when they select the input layer in the interface. If they lack the privilege to do so, stop them there, before they go on to fill out the rest of the parameters and run the tool.
If the above is not feasible, then inform the user why Extract Data failed with a more specific error message, such as, "You do not have permission to extract data for export from the selected input layer."
