While you cannot "freely" download a full, licensed version of Office from Microsoft without a subscription or product key, you can still access the installer files if you have a valid license: Microsoft Office 2016 and Mac OS X 10.11.6 El Capitan
Still functional on El Capitan, but extremely outdated and lacks modern features. How to Download and Install Microsoft Office For Mac Os X 10.11 6 Free Download
This is the most recent version that runs on El Capitan. While you cannot "freely" download a full, licensed
While compatible, support for this version ended in 2017, meaning it no longer receives any security updates. Microsoft Office For Mac Os X 10.11 6 Free Download
The last version of Microsoft Office that is fully compatible with OS X 10.11.6 is (specifically version 16.16.27 ).