New documentation available at https://docs.openkm.com/kcenter/
The documentation at the https://www.openkm.com/wiki is definitivily deprecated.
Consider only use it, if you are user of OpenKM version 6.2 and older.
Click in the banner to close the warning.
Go to Window / Preferences / Java / Installed JRE. You must have JDK 1.6 defined here: