When using Chaos Cosmos, you may find that assets are present in the Chaos Cosmos web service that aren’t available in the in-app Cosmos Browser. This is normal and expected because the Chaos Cosmos web service doesn’t know which V-Ray and host platform you would like to use and cannot filter the library accordingly. For example, there are some assets that require V-Ray 6 and therefore you won't be able to import them in V-Ray 5.
Chaos recommends using the in-app Cosmos Browser instead of Chaos Cosmos web service. The in-app Cosmos Browser displays only the compatible assets for your host application and V-Ray version, so you can be assured that every single asset will work properly.