I am trying to sync my Outlook Desktop and ical calendars

@Katie Yan said

I don't think the apps are synced.

Yes. It sounds like New Outlook for Windows did not register your MS 365 account correctly.

1 -- Try Removing the MS 365 account and then adding it back.

Are there any errors when you are adding it?

2 -- If that doesn't work, then try resetting your New Outlook for Windows back to it's initial install state. This erases all the locally cached data, settings, and email accounts. i.e. It's like you are starting New Outlook as if it had never been used on your PC.

See the answer by "Hornblower409 Dec 11, 2025" in
https://learn.microsoft.com/en-us/answers/questions/5655980/outlook-starting-error-repair-reinstall-reset-does

Calendar and contact sync between Outlook desktop, Outlook on the web, and other calendars (like iCal) depends on how the account is configured and which protocols are used.

Key points for this scenario:

1. Outlook desktop → Outlook on the web sync
   • Calendar and contacts only sync when the account in Outlook desktop is connected to a server that supports Microsoft Exchange ActiveSync / Exchange (for example, Microsoft 365 work or school, or Outlook.com).
   • If the account in Outlook desktop is configured as POP or IMAP, only email syncs. Calendar and contacts created in Outlook desktop stay local and will not appear in Outlook on the web.
   • To have a single calendar across desktop and web, the mailbox must be an Exchange/Microsoft 365 mailbox and configured as such in Outlook desktop.
2. Why iCal (.ics) is not importing as expected
   • POP/IMAP accounts cannot sync calendar and contacts; they only sync email. Even if an .ics file is imported into Outlook desktop under a POP/IMAP profile, those events will not sync to Outlook on the web.
   • To make iCal events visible in Outlook on the web, import or subscribe to the calendar directly in Outlook on the web:
     • Save the .ics file locally.
     • Sign in to Outlook on the web.
     • Go to Calendar → Add calendar → Upload from file.
     • Choose the .ics file, select the target calendar, then Import and Save.
   • Alternatively, if there is an online calendar URL, use Subscribe from web in Outlook on the web to keep it updated automatically.
3. Requirements and limitations
   • An email provider that uses Microsoft Exchange ActiveSync is required for calendar and contact sync. IMAP/POP accounts cannot sync calendar/contacts.
   • Starting March 1, 2026, devices using ActiveSync versions lower than 16.1 will no longer connect to the service; devices must be on supported ActiveSync versions.
4. Recommended approach
   • Ensure the company account is set up as an Exchange/Microsoft 365 account in Outlook desktop (not POP/IMAP) so that calendar and contacts sync with Outlook on the web.
   • For managing email, calendar, and contacts across devices, use Outlook on the web and, on mobile, Outlook for Android or Outlook for iOS.

References:

• Can't sync calendar and contacts with my phone or tablet
• Import or subscribe to a calendar in Outlook.com or Outlook on the web
• Add a calendar in Outlook.com or Outlook on the web