Unable to Figure Out How to Connect to Fastmail

I want to use KOrganizer for integration with Plasma 6. I can’t set up my calendars from Fastmail as I’m prompted with this:

If I do it manually, https://caldav.fastmail.com/ does not connect with a 404 error.

I am on KDE Neon with Plasma 6.4.5 and KOrganzier 25.08.01.

Thank you!

it’s possible the wizard isn’t working properly for fastmail.

try canceling out of the wizard and use the manual configuration dialog.

I’m sure people have reported successfully using fastmail calendars with version 25.08.01

found in a bug report: