You can simply assign an ASL interpreter by simply allowing the ASL interpreter to join your meeting/webinar and from there you can just simply spotlight the interpreter.
Spotlight video puts up to 9 participants as the primary active speakers for all participants, and participants will only see these speakers. Spotlighting can also be done during screen sharing. This feature is often used to spotlight a keynote speaker.
That's good to hear. To clarify Zoom doesn't provide interpreters, the language interpretation will only allow you to invite your own interpreters to your meetings/webinars. This means that you really need to have your own interpreters.
To invite your ASL interpreter to your meeting you just need to provide the meeting link or the meeting ID and passcode for your ASL interpreter to use.