I was unexpectedly granted access flying EU J on KLM a few weeks ago. It isn't listed on the KLM website, but the sign in front now includes KLM on the long list of airline partners. While it certainly isn't world class, as a generic third party lounge, I found it to be vastly superior to waiting in the ever-crowded SPU departure hall. This airport was designed for when HR was not part of Schengen, and the gates preceding passport control were standing room only. Despite the crowding at the gates, the lounge was virtually deserted and quite peaceful. The food selection is sparse, but they had some sandwiches and pastries available, in addition to a decent selection of soft drinks and alcohol. The restrooms are just outside the lounge entrance, clean with no lines.