I'm using Etsy's API to create a guest cart in React. Their documentation is here: https://www.etsy.com/developers/documentation/reference/guest
You have to have production access to do this, and after a couple of applications, I managed to get granted this. They said that it doesn't require authentication, but when I tried to create a guest using the api via this url: https://openapi.etsy.com/v2/guests/818718aa-996c-11eb-a8b3-0242ac130003/claim?api_key=[my_api_key], the result was 403 and "This method requires authentication."
Does anyone else have experience with Etsy's guest API, or what kind of authentication I can use, based on the documentation? Etsy's people have not responded to my inquiries in weeks.