Hi Jacob,
I assume that you have a version of Outlook for Mac already. To install the new Outlook for Mac, please follow the instructions in this article: https://support.office.com/en-us/article/Running-Office-for-Mac-2011-side-by-side-with-Outlook-for-Mac-for-Office-365-dbea7d44-b212-4d8b-85bd-2722ca671c0f?ui=en-US&rs=en-US&ad=US . Click the second install instructions here if you are a Business Premium user.
If you don't have an Outlook installed on your Mac, please refer to this article for dedicated information: http://blogs.office.com/2014/10/31/new-outlook-mac-available-office-365-customers/
Please let us know if this answered your question.
Thanks,
Jeremy Ren