How to create an AI enemy in a resogun-style, circular side scroller

We have a large circular map area and a player that can move in either direction around it using a spline.

It’s easy enough to get this working with something player controlled but I’m unsure on how I would blueprint an AI on this same circle. I can’t seem to get it to work with a spline but maybe there’s an alternative I’m overlooking.

Thanks.

On a side note, how would you have projectiles follow this same circle rather than going straight?