You will be presented with the following screen. Click on Create new App.
You will be shown a form where you have to enter Application Name and Development Slack Workspace. Fill the form with appropriate information and click on Create App.
After creating the slack application, you will be brought to Application Management page. Scroll down to “App Credentials” section. Here you will find given Client ID and Client Secret for your slack application.
Copy these credentials and keep it handy because you will need it in the next step.
Go to OAuth & Permissions.
Add Redirect URL: In slack application's Redirect URLs section, Click on Add New Redirect URL and enter the same from the MiniOrange Joomla OAuth Client. Click on Save URLs.
Scope: Go to OAuth & Permissions, select scope from Select Permission Scopes dropdown list and Save Changes. Identity basic is required scope.