Hi...

I have encountered the same problem as MDLQA-9651. I can't seem to figure out if it is a Microsoft issue or a Moodle issue.

Step by step guide for reproducing the issue.

1) First navigate to https://demo.moodle.net
2) Login with credentials: admin/sandbox
3) Goto Site administration => Plugins => Repositories => Manage repositories
4) Goto Microsoft OneDrive and enable the it, by selecting: Enable and visible
5) Rightclick the link in the first line of the text "with Microsoft" and press open in new tab.
6) Click the add app button and give your app a name (Test) and press "Create application"
7) Copy the Application ID to a textfile for later
8) Click the "Generate New Password" button and copy the password from the box to the textfile aswell and click OK
9) Click the "Add platform" button and select "web"
10) Paste in the callback url from the Moodle setup page (https://demo.moodle.net/admin/oauth2callback.php)
11) Click save at the buttom
12) Close the tab and go back to the Moodle page.
13) Insert your Application ID in Client ID field from the textfile and your password into the secret field also from the textfile, click save
14) Click "Cources" and select "My first course"
15) Turn on editing and click "Add an activity or resource"
16) Doubleclick on file and navigate to "Select files"
17) Click the "Add" button and select "Microsoft OneDrive"
18) Click "Login to your account" and click "Yes" in the popup