Create Users procedure error

I'm trying to create a new user on a neo4j CE database using the following:

CALL'username', 'password', true);

Following these instructions from the Neo4j manual:

But I get the following error:

There is no procedure with the name `` registered for this database instance. Please ensure you've spelled the procedure name correctly and that the procedure is properly deployed.

Can anyone explain why this isn't working?

Neo4j CE 3.5
Red Hat Enterprise Linux Server release 6.9 (Santiago)