Can Todoist be used to manage the tasks in Exchange as well? I am on Exchange and use a Mac
When you refer to exchange, do you mean in terms of how the mail is managed, or that you are using "Outlook"? As we do not have support for the Mac version of Outlook at this time.
You can learn more about the options here. https://todoist.com/blog/2013/01/zero-inbox-policy-with-todoist/