This is the 9753rd most frequent Spanish word.
australianos
Australians.
Here, 'australianos' serves as an adjective, describing the friends as being from Australia.
Me encontré con unos amigos australianos en la conferencia.
I met some Australian friends at the conference.
In this instance, 'australianos' is again used as an adjective, qualifying 'artists' as being from Australia.
Esta compañía tiene una colaboración con artistas australianos.
This company has a collaboration with Australian artists.
In this sentence, 'australianos' is used as a noun to refer to people from Australia, specifically emphasizing the collective characteristic of loving outdoor activities.