Will Adobe CS5 with Java SE 6 runtime work on 10.11 El Capitan?
Yes, you will need to install the Java version from https://support.apple.com/kb/DL1572?locale=en_US

From that link:

"Java for OS X 2015-001 installs the legacy Java 6 runtime for OS X 10.11 El Capitan, OS X 10.10 Yosemite, OS X 10.9 Mavericks, OS X 10.8 Mountain Lion, and OS X 10.7 Lion.

This package is exclusively intended for support of legacy software and installs the same deprecated version of Java 6 included in the 2014-001 and 2013-005 releases.

Quit any Java applications before installing this update."

After installing and restarting you can use the Java preferences pane in System Preferences to control which Java version you would like to use.