On the Kalenders page, select a calendar you like.
Click Selecteren.
If you are not logged in to WebCal.Guru, you will not be able to modify subscription settings and you will have significantly smaller selection of calendars. In this case, jump directly to Step 4.
Adjust the subscription settings if needed and click Aan Mijn kalenders toevoegen.
You will be taken to Mijn kalenders page. On the calendar you just added, click and select Adres naar klembord kopiëren.
Log in to Outlook Live Calendar.
Click Add calendar.
Go to the empty field with Example... and paste the clipboard contents there. The result will look something like https://www.webcal.guru/....
Enter the Name, Color and select a Charm for the calendar. Outlook will not use the color and name you may have set when subscribing the calendar. Finally, click Import.
Updated 8 Feb 2023