In the new Office 365, Mac users can download Office for Mac 2011.
So what to do if you want your Office for Mac now, and your tenant hasn't yet been upgraded to the new Office 365 experience?
If your are an existing Office 365 E-plan customer, and your tenant hasn't yet been upgraded to the new Office 365 experience, your tenant is in what we call Pre-Upgrade. Pre-upgrade Office 365 tenants will not expose links to end users for Office for Mac 2011.
However, if you want to use Office for Mac 2011 with Office 365 activation, you can download the DMG installation package from this link. That will download an English-US version of Office for Mac 2011 SP3 which will activate against an Office 365 tenant Pre- or Post-Upgrade for users with rights to Office Professional Plus or Office 365 ProPlus desktop apps.
These will also count against the five installations per user and the interface to manage deactivation of Office apps will be available to users once pre-upgrade tenants have been upgraded.
- Office 365 Technical Blog, Jeremy Chapman blog post on this topic (and how to get the new Office client for PCs) - link