Login to your LinkedIn account or register in the system, then go to https://www.linkedin.com/developer/apps
Press "Create Application" button.
Fill in all necessary fields and upload your logo image.
As soon as all information has been entered, click "Submit". Once your application has been created, you will see the secret keys that need to be entered in the corresponding fields of the extension settings in the admin panel of Magento®. Also, specify the necessary redirect URLs that can be found in the admin panel settings for LinkedIn.