For example Handoff and Continuity, which were introduced with OS X Yosemite, require hardware that supports Bluetooth LE. Keep in mind that the older your Mac, the greater the possibility that some features won’t work. Here are some tips for freeing up storage space.
As for available storage space, 8GB is enough to run the installer, but more is always better. You can run a Mac with 2GB of memory, but this is a good opportunity to upgrade to 4GB or 8GB. The general minimum requirements call for 2GB of memory, 8GB of available storage, and an Internet connection for some features.
MacBook (Late 2008 Aluminum, or Early 2009 or newer).These Macs are compatible with El Capitan.