Creating a LinkedIn App:
So, when you have decided to create a LinkedIn App, you would have to first visit thissite.
Then login your LinkedIn account for accessing the developer page.
Now, you would be taken to the developer page.
Now, click on Create Application link.
Then when the page loads type in all the mandatory information.
Also, check whether you have entered the correct URL of your website and do a double check. (Make sure that you have entered the web address actually the way it is. Only then the App would work correctly.)
Now, click on Submit button.
After this you would see an app listing page containing all the needed information for you to integrate that App into your website.
Now, enter your website URL in the OAuth 2.0 field. Make sure that is exactly the same for the application to work or else you would get an error message when you try to connect.
Then you would have to copy the API Key and Secret Key into the LinkedIn App settings which is found within the Plugin settings page.
As you copy paste all the needed IDs and Keys, make sure that there is no empty spaces. If there is any empty spaces then the application would not work.
After this click on Save Changes found in the plugin's settings page.