If you are an Internet Explorer 11 user, browser security restrictions may prevent you from using Apply With LinkedIn. You can modify your security settings to enable this feature.
In Internet Explorer 11...
1.Click the Gear Icon > Internet Options > Security > Uncheck "Enable Protected Mode"
2.Gear Icon > Internet Options > Security > Trusted Sites > Sites > In the "Add this website to the zone" input text box, type "*.linkedin.com" > Uncheck the box that says "Require server verification"