Unable to add the Monumental+ Sports app

Welcome meven89143​ 

Looks like you're unable to add the Monumental Sports app on your other Roku device. If it won't let you add the app through the Roku device itself,  you can try to add it through, Roku mobile app instead. 

Here are the steps: 

1. Launch the Roku Mobile app on your mobile device. 
2. Browse the categories and genres, search to find a specific app, or go to the Store.
3. Select an app to view more information
4. Select 'Add App' and follow the on-screen instructions to install it on your Roku device.

For more details, visit this link. 

Roku Community Team 

As far as I know, the Monumental Sports app limits the number of devices per account. You will need to remove it from one of your other Rokus before adding it to a third one.