Let me start by making it crystal clear that you will only be able to host a LinkedIn Audio Event if you have 'creator mode' enabled. However anyone is able to join a LinkedIn Audio Event and joining events together with creator mode enabled is a really great way to ensure that you get the ability to host LinkedIn Audio earlier than most.

Once 'creator mode' is on, LinkedIn will eventually and automatically provide you with the ability to host a LinkedIn Audio event. There's no timeframe on how long this will take, I had creator mode on for months and only after attending several LinkedIn Audio events and checking daily did I notice that 'Audio Events' was enabled. I received no notification and there was no indication that I had gotten the feature. Now I have LinkedIn Live, Audio Event and Newsletters as part of my Creator Tools.