Both should have showers open, and currently the non-Schengen lounge should be borderline deserted given the COVID restrictions on travelling. There is a small footnote in the lounge.klm.com page stating you can pay by the door not being an FB member or flying SkyTeam.

EUR 50 is the price that I know, I just believe this is better value given all the extra amenities at the lounge, but maybe it's just me.

I'd contact KLM via any social media for specific updates - in my experience, they indeed do reply within an hour.