Different experience here. Travelled AtlasGlobal in J on a KL-codeshare a while ago. They sent me to the wonderful Aspire lounge, and I tried the Crown Lounge, but to no avail, even after showing the app with KL number.
My brother though, who was travelling on the same flight, tried it with another agent, and he got in...
AtlasGlobal had priority check-in and security, and the cabin was better than the KL EuroBiz 737.