How can I subscribe a new email to a list using the API?

How can I subscribe a new email to a list using the API?

Hi,

I'm trying to subscribe a website user to a list using the API, but is there any example or guide on how to do this? All documentation I can find seems outdated or overly complex ( I really hope I don't have to retrieve an oauth2 accesstoken every time a website user wants to subscribe to our mailinglist).

Hoping to hear from you soon.

Kind regards.