Sync the macOSX Calendar App with the Disroot cloud.
This will allow you to check, update and remove your events from any computer with an internet connection. Also it will enable syncing calendar items with your smartphone and/or tablet. Once it runs, and nothing breaks, you'll forget it is there.
A window opens called 'Add CalDAV account'
From the drop down menu:
Account type: Advanced.
Username: your username (without @disroot.org)
Password: your password
Server Address: cloud.disroot.org
Server Path: remote.php/dav/principals/users/USERNAME/
(replace USERNAME with your username)
Port: 443
and Use SSL ticked.
Click Sign In
!
Now your calendar is added. If you now open the Calendar App, two new calendar will show in the left column. You can change the name and colors in the Calendar App preferences.