Open the My Apps Portal and log-on with your Organizational Account to Office 365 using this link https://account.activedirectory.windowsazure.com.
Pick your account.
Make sure to use the "Organizational Account" option and click on "Add App".
This little window will pop up. Click on "Add".
A message appears, click on "OK".
Now you can see the pending approval request for the application.
You will get a notification after approval and it appears under your Apps.