Step 1: Go to App Access Control
Have your admin log into App Access Control.
To manually get there to go Security > API Controls > App Access Control
Step 2: Click "Add App"
Click "Add app" then "OAuth App name or Client ID"
Step 3: Search Using Our ID & Select "Mailstand"
In the search bar, search using our ID:
It will look like this:
Then hit "Select"
Step 4: Select The Auth
Click on the access like this
Step 5: Hit Trusted
Then you're all set! You will then be able to upload via OAuth with no problem.