5th Generation Nano iPod rejects attempts to download library books via Overdrive

I have been downloading library books via Overdrive for a long time. My process is suddenly no longer allowing me to download my books and when they have downloaded the audio is echoing. I have no idea what the correct "settings" in preferences should be. I've tried switching to OneClickDigital and it rejects my attempts also. If you download library books to the same 5th gen iPod device I'd love to hear how you have set yours up.

Many thanks for your attention.