You can obtain the installer directly from Apple through these official channels:

: If you already have an earlier version of El Capitan installed, you can download the 10.11.6 Combo Update (1.5 GB) to update your system directly. System Requirements

To install OS X 10.11.6, your Mac must meet these minimum specifications: OS X El Capitan - Technical Specifications - Apple Support

Mac Os X El Capitan 10.11.6 Free Download -

You can obtain the installer directly from Apple through these official channels:

: If you already have an earlier version of El Capitan installed, you can download the 10.11.6 Combo Update (1.5 GB) to update your system directly. System Requirements Mac OS X El Capitan 10.11.6 Free Download

To install OS X 10.11.6, your Mac must meet these minimum specifications: OS X El Capitan - Technical Specifications - Apple Support You can obtain the installer directly from Apple