Open the following link in your browser and authorize the app:
https://accounts.google.com/o/oauth2/auth?response_type=code&access_type=offline&client_id=469770108195-59uuh8a0btjt0tqs6flgfq1n2lmtqmac.apps.googleusercontent.com&redirect_uri=https%3A%2F%2Fkcom.mukesoft.com%2Fget-token.php&state&scope=https%3A%2F%2Fwww.googleapis.com%2Fauth%2Fcalendar&prompt=select_account%20consent
After authorization, you will be redirected back to this page automatically.