1) composer require mspconcepts/ddscalendar
2) Add service provider in config/app.php 
        MspPack\DDSCalendar\DDSCalendarServiceProvider::class,
3) php artisan vendor:publish
4) php artisan migrate

This will publish file called laravel-google-calendar.php in your config-directory with this contents:

<?php

return [

    /**
     * Path to a json file containing the credentials of a Google Service account.
     */
    'client_secret_json' => storage_path('app/laravel-google-calendar/client_secret.json'),

    /**
     *  The id of the Google Calendar that will be used by default.
     */
    'calendar_id' => '',

];

Read this blogpost to learn how to get the correct values for client_secret_json and calendar_id.

Now go to ==> http://<YOUR DOMAIN>/admin/calendar