I couldn't find any good tutorial for doing this so here's a quick one.
- Go to System Preferences -> Internet Accounts -> Click Exchange
- Enter your details
- Your info will fail to verify. This is expected.
- Enter the information like in the screenshot:
- Enter your email address as the username
- Enter your password. If you have Two Factor Authentication enabled, create a one-time app password here: https://account.live.com/proofs/AppPassword
- Enter the same URL for Internal and External: https://outlook.office365.com/EWS/Exchange.asmx