Error installing F-Droid client on a Fire Stick

One more issue, have installed the F-Droid 1.15.6 client which works on that device but enabling F-Droid Archive repo is a problem. I have toggled it enabled but apparently it still isn’t enabled. When I tap the line with the F-Droid Archive repo to display the details of the repo it shows a QR code and says “Diese Paketquelle wurde noch nicht verwendet. Um … muß sie aktiviert werden”.. as far as my German goes it means that repo wasn’t used yet and must be activated. Just how do I activate it? The toggle is on​