If somebody needs access to another user's onedrive you can create and share the link to do so.
Go to the O365 admin portal. Find the user in the active users list. Click on the Onedrive tab and click on the Create link to files button. This will generate a link to the users onedrive. However only admins will be able to view the link, you will need to grant permissions for the person making the request.
Open the link and then go to the settings cog in the top right and then onedrive settings.
Now go to more settings and then site collection administrators
Then just type the name of the person who needs access and click ok
The requesting user will now have access to the onedrive files and folders. Share the original link to whoever needs it.