Might be a stupid question actually however how do I import Lemmy’s RSS into an RSS-App?

I’m using “Feeed” RSS app on iOS. I downloaded the RSS-Feed link of for example Books.ml but when I try to import it into the app, it says “No data”

I have added an image of what, I mean.

Am I doing it wrong?

EDIT: This might be the wrong community, I have realized. But not sure which community, I should go to otherwise.