You either need to be an admin or need to be in a group that grant you access to it.
To do this an admin will need to create a group and enable the following:
Under report access click on Customize for Report suite tools
Then under Tools and Reports select Data Feeds Manager
Make sure your login is added Group member
Save
Then you will have to Logout then login once the above is done, doc explaining how to open data feeds manager Open the Data Feed Interface