from linkedin.linkedin import (LinkedInAuthentication, LinkedInApplication,
                               PERMISSIONS)


if __name__ == '__main__':
    API_KEY = 'wFNJekVpDCJtRPFX812pQsJee-gt0zO4X5XmG6wcfSOSlLocxodAXNMbl0_hw3Vl'
    API_SECRET = 'daJDa6_8UcnGMw1yuq9TjoO_PMKukXMo8vEMo7Qv5J-G3SPgrAV0FqFCd0TNjQyG'
    RETURN_URL = 'http://localhost:8000'
    authentication = LinkedInAuthentication(API_KEY, API_SECRET, RETURN_URL,
                                            list(PERMISSIONS.enums.values()))
    print(authentication.authorization_url)
    application = LinkedInApplication(authentication)

from linkedin.linkedin import (LinkedInAuthentication, LinkedInApplication, PERMISSIONS)

if __name__ == '__main__':
  
    CLIENT_ID     = '############'
    CLIENT_SECRET = '#############'
    RETURN_URL = 'http://localhost:8000/callback/'
    
    authentication = LinkedInAuthentication(
                        CLIENT_ID,
                        CLIENT_SECRET,
                        RETURN_URL,
                        PERMISSIONS.enums.values()
                    )
    
    print(authentication.authorization_url)
    application = LinkedInApplication(authentication)

Update authentication.py