Qiscus SDK provide Client Authentication called `setUser`, you can use this method to login or register user when unavailable.
Qiscus Web SDK : https://www.qiscus.com/documentation/web/latest/getting-started#client-authentication
Qiscus Android SDK : https://www.qiscus.com/documentation/web/latest/getting-started#authentication
Qiscus iOS SDK : https://www.qiscus.com/documentation/ios/latest/getting-started#authentication
Qiscus Rest API : https://www.qiscus.com/documentation/rest/latest/user#login-or-register
You also can create user via Dashboard under Users page. Read details about Identity Management on this blog post.