Given that New Amsterdam airs live on NBC, new episodes of the series can be found the next day on Peacock, which is NBC’s streaming platform. Collider notes that you must have a Peacock Premium subscription for this.

Peacock is where you’ll find old seasons of the show as well.

It seems that the only way to watch the show on Hulu is with a Hulu + Live TV subscription, so you’d be watching new episodes lives as they air. (Other platforms with live TV options where you can watch the show as it airs include YouTube TV, FuboTV, and DirectTV Stream, per Grounded Reason.)

Source: https://www.distractify.com/p/why-is-new-amsterdam-not-on-hulu