How to get pages for MacOS 10.11.6

The only full version of Pages for installation is in the Mac App Store, and requires that you have High Sierra 10.13 or later already installed. You can purchase the retail iWork '09 DVD from Amazon/Ebay resellers, and once installed, follow that up with the downloadable, Apple iWork 9.3 updater. In the end, you will have the most recent updates for the iWork '09 applications (circa 12/2012), with more ease of use, and functionality than the current Mac App Store release of Pages.

A consequence of Pages '09 is that it cannot directly open any documents created with versions of Pages introduced since Oct 2013. Then, you will need to use Pages for iCloud, or if you have it, Pages for iOS v4.3 or later.

If you had Pages v5.6 or 5.6.2 for El Capitan, and it remains on a Time Machine backup, you can restore Pages to your /Applications folder in that manner too.

I highly recomend you use the iWorks '09 v4.3 for your set-up.

It may be 10 years old but the great thing is it hasn't been upgraded by the current Team Apple.

And that makes it substantially better and more productive. I refuse to touch anything put out by Team Apple in the last decade, it has mostly been down hill.