SupportCandy REST APIs are only available for registered users. Therefore, you must authenticate the user for every endpoint our REST APIs support.
There are many ways you can authorize the user, as given below:
1. Basic Authorization
WordPress provides built-in support for Basic Authorization using an Application Password. Here are a few links to learn how to authenticate users using Application Passwords.
https://make.wordpress.org/core/2020/11/05/application-passwords-integration-guide/
https://artisansweb.net/how-to-use-application-passwords-in-wordpress-for-rest-api-authentication/
2. Authentication plugins
It is not recommended to use basic authorization for the production environment. A few popular WordPress plugins provide secure authorization methods like JWT, OAuth 1.0, OAuth 2.0, API Key, etc. Here are a few authorization plugin links:
https://wordpress.org/plugins/jwt-authentication-for-wp-rest-api/