Hi I had the same problem and removed the X-Appery-Brand and now I have the following error:
{ 
     "status":401, 
     "uri":"https://api.appery.io/rest/1/db/files", 
     "response":{ 
         "code":"DBFL001", 
         "description":"unauthorized" 
     } 
 }
Please advise, thank you?