For dummies like me - you can't subscribe to magazines via the Artemis app yet, so subscribe to this ArtemisQuiver magazine using the web interface. You'll then see this pinned post in your Posts list in the app.
Note: ArtemisQuiver doesn't immediately appear in your list of magazines that appears when you click on Home. Not sure how you force a refresh of your magazine subscriptions in the app. Whoops - this is a known issue: https://github.com/hariettem/Artemis/issues/63