I worded my question the way I did because my wife and I were SkyTeam Elite Plus traveling in Comfort+ but hoping for Global Upgrades to clear. We went to the “SLOW” lounge and asked if we were eligible. The lounge dragon politely explained that it was a contract lounge and only open to DeltaOne pax.
The lounge access tool on delta.com indicated we weren’t eligible for any JNB lounge, but I have found that tool incorrect at times, so I thought there was no harm in asking. Ultimately we did clear into DeltaONE, but too late to use a lounge. BTW we both thought that the DeltaONE “suites” were nicer than the KLM equivalent, but we also agreed that the overall KLM Business Class experience was superior to DeltaONE.