Insert new App into Space

hi all, when creating a new app in an existing space, we are getting an error.
any suggestions or advice on how to resolve this:

api endpoint in postman: {{base}}/api/spaces/60/apps

and we are sending the following based on api documentation
https://pingerws.azurewebsites.net/docs/post/spaces/id/apps

{
  "name": "Files",
  "guid": "6293709f-84da-452a-b1ea-07ff32b192e1"
}

result:

{
 "status": 500,
 "message": "Value cannot be null.\r\nParameter name: app"
}

a related issue is that we create the space and then when we try to add the files app, it creates a new space with the files app