Similarly, you can't install El Capitan unless you have 2 GB RAM on your Mac. Without enough RAM, trust me, you can't even run your native operating system smoothly. RAM is the temporary memory that supports the system to run apps and programs efficiently.

Mac Pro introduced in early 2008 or later.

Mac mini introduced in early 2009 or later.

MacBook Pro introduced in mid-2007 or later.

MacBook Air introduced in late 2008 or later.

MacBook introduced in 2009 or later, plus MacBook (13-inch, Aluminum, Late 2008).

The followings are devices that are compatible with OS X El Capitan. For instance, you can't use AirDrop on your Mac if you don't have a WiFi network compatible with PAN. Most of the Mac models can install and run OS X El Capitan, but in some devices, you can't use full features of this OS due to hardware limitations. You might have to free more space to run your Mac more smoothly because low space slows down system performance. However, that's the space you need to install El Capitan on your Mac. You can't install OS X El Capitan unless your Mac has a free space of 8.8 GB. However, if you are planning to update your Mac to OS X El Capitan, your device must fulfill the following requirements. Improved window management, quick and responsive interface, spotlight search, and enhanced graphics were the prerequisites of El Capitan OS. OS X El Capitan (10.11) was launched on 25 September 2015, and it is an improved version of OS X Yosemite (10.10). Is OS X El Capitan Still Available for Your Mac?

Recover Lost Files After OS X El Capitan Update.

Is OS X El Capitan Still Available for Your Mac?.

How do i update my mac from 10.11 6