Error Message:
Error while creating new document. Error message: Not allowed to insert > Document Request record.

App Expert Reply: 
– Check that user has access to Document Request object. Or open sharing settings up for the object by going to Setup > Security Controls > Sharing Settings > Document Request > Change to a Public setting.
-If error persists after you have given user “Read” and “View All” for that object, you  should give them “Create” permissions to the Document Request object to resolve error.