At the openhab> prompt, try these commands:
feature:install openhab-runtime-compat1x
bundle:install https://openhab.ci.cloudbees.com/job/openHAB1-Addons/lastSuccessfulBuild/artifact/bundles/binding/org.openhab.binding.ekey/target/org.openhab.binding.ekey-1.9.0-SNAPSHOT.jar
And put its configuration in a file called conf/services/ekey.cfg but leave off the ekey: from the beginning of each line. Also, don’t leave spaces as the first characters on the lines.