While Reclaim is only for Google Calendar users today, it is technically possible for us to sync non-Google Calendars if they've been shared with a Google account that you've given Reclaim access to. Reclaim is essentially using your Google authentication as a way to gain access to that shared calendar, even though it originates in another calendar platform.
We don't highly recommend this method for non-Google calendars, as it has some known issues around refreshing -- it can take up to 24 hours for changes on a shared calendar from iCal or Outlook to reflect in Google, and so it can often be an unreliable method of syncing events. That being said, it is possible, so if you want to try it out here are some steps to get it set up.
Syncing a shared calendar
First, you have to make sure that the calendar you want to connect is shared with your Google account that you're using to sign up for Reclaim. Here's a guide on how to share an iCloud calendar with your Google account, here's one for sharing an Outlook calendar with your Google account, and here's one for sharing a Google Calendar with a Google account.
You can sync a shared calendar post-onboarding by going to Calendar Sync. Click the "+ Create Sync" button, and then select the account that you shared the calendar with. Then, find the calendar that you shared and select it as a source:
From here, you can complete the setup and set any preferences you'd like for that shared calendar to be synced.