Pages, Numbers, and Keynote come free with your Mac and run flawlessly on Sierra. They can export to Microsoft format easily.
Since you cannot download a "free" version of the 2010/2011 suites legally without an existing license, your best options involve using legacy installers or modern subscriptions.
: A Mac-exclusive feature in Word and PowerPoint to eliminate distractions during writing or presenting. Visual Basic for Applications (VBA)
The table below shows the last compatible versions of Microsoft Office for your operating system:
If your workflow is deeply integrated with Microsoft Office, these are your best options: