This tutorial is for Siberian CMS Editor Image Uploader Module. You will find more details here: https://extensions.siberiancms.com/downloads/image-uploader-editor/
Sign up /sign in to your Imgur account by visiting: https://imgur.com
Now register your application by directly visiting this link: https://api.imgur.com/oauth2/addclient
Give your app name like "Demo App / Image Uploader"
Authorization type: OAuth2 Without a callback url
Your email and description like "image uploader"
Checkmark "I'm not a robot" captcha and click on the submit button.
Now you will get Client ID. Copy-paste it in Backoffice >> Manage >> Modules >> Image Uploader