Recent macOS and iOS versions (iOS 11, iPadOS 13.1, and macOS 10.14 or later) have native system-level support for Microsoft Exchange/ActiveSync accounts, which allow use of most features of mail/contacts/calendaring. Some features may still require the use of official Microsoft web or PC apps to access some functionality.

On iOS and iPad OS, accounts are added through the Settings app. Apple provides more instructions here: https://support.apple.com/en-ca/HT201729

On macOS, an account can either be set up through System Preferences/Settings, or through an individual app. Microsoft provides instructions here: https://support.microsoft.com/en-us/office/set-up-email-in-mac-os-x-mail-de372dc4-9648-4044-a76c-e8a60e178d54 and Apple has general steps for adding an account here https://support.apple.com/en-ca/guide/mac-help/mh35565/13.0/mac/13.0