The URL that you use to complete OAuth authorization needs to be publicly accessible. That way, you can complete the OAuth authorization. From there, you could pass the access token to a private server but in order to use the API, you’ll want to open the firewall to the *.zoom.us subdomain.
Alternatively, you can create a JWT App if the users that you would be accessing are under your account. An OAuth app will allow you to make requests on behalf of other users/accounts.
Thank you for reaching out to the Zoom Developer Forum. Please send an email to developersupport@zoom.us with a link to this thread. In that ticket, please provide the email of the app owner.
I’ll investigate further in the ticket with that information.
Are you seeing this issue when using your development or production credentials? If you changed the redirect URI, it won’t have an effect until the app is approved.
Got it, I’m glad that helped then! I’ll go ahead and close this topic now but feel free to open a new topic if you encounter any further issues or questions.