You must have macOS Sierra or later installed to get current versions of Pages, Numbers, and Keynote from the Mac App Store. Apple does not keep past versions of these applications for user access.
Your best bet is to access your last Time Machine backup before you formatted your Mac, and restore Pages, Numbers, and Keynote from the /Applications folder. The last revisions for El Capitan were Pages v5.6.2, Numbers v3.6.2, and Keynote 6.6.2.
If you do not have these on a Time Machine, or other backup source, then you are done, short of using the diluted Pages, Numbers, and Keynote for iCloud applications.
If you had Pages, Numbers, and Keynote from the iWork '09 DVD installed, then reinstall from the DVD, but then apply the iWork Update 9.3 to bring these iWork '09 DVD only applications to their last updates: Pages '09 v4.3, Numbers '09 v2.3, and Keynote '09 v5.3. These iWork '09 applications cannot open documents created/edited by newer application versions, or their iCloud counterparts.