Goto your Restyaboard installation root directory. e.g., directory: /usr/share/nginx/html/restyaboard/
Extract/unzip the purchased plugin zip into the Restyaboard installation path
Give file permission to extracted files. e.g., chmod -R 0777 client/apps/r_user_ical_feed/
Execute the r_user_ical_feed.sql in your Restyaboard database, located in client/apps/r_user_ical_feed/sql/ directory
Add the line rewrite ^/ical/([0-9]*)/([a-z0-9]*).ics$ /server/php/plugins/UseriCalFeed/ical.php?user_id=$1&hash=$2 last; after line 23 in the Restyaboard configuration file which is in the /etc/nginx/conf.d folder and restart the Nginx by systemctl restart nginx
After above process, clear the browser cache and login again to view the installed User iCal Feed plugin on your Restyaboard.
After login, please click the user profile or user icon in the footer menu and click the profile options and it will direct to the user profile page.
Now click the tab Cards and under the tab content, you can see the Copy iCal User Feed button.
After clicking the button, the dropdown will appear and the iCal feed URL will be in the input and you can copy the url and enter it in the URL for Google calendar option.