Once added, the channel will not immediately appear on your Roku device. Your Roku device checks every 24 hours for any new channels you have added from the website and automatically installs them. If you would like to download immediately, go to your Roku device and select Settings > System > System update > Check now.
Support for the Roku 2 XD (model 3050) ended a few years ago. Roku hasn't provided OS updates in years, and many app developers have dropped support for the devices. Discovery+ didn't even come along until years after support for that device ended, so it never officially supported it.
The device is 9-11 years old, depending on when it was first purchased, and while it may still be chugging along, will not run many apps. It may be time to think about upgrading.
DBDukes Roku Community Streaming Expert Note: I am not a Roku employee.
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