From Lazarus version 1.4, this package should be replaced with DateTimeCtrls Package, which is included in Lazarus distribution.
The controls in DateTimeCtrls package replace controls from old ZVDateTimeCtrls. ZVDateTimeCtrls package will be no longer updated, so please switch to DateTimeCtrls Package. If you have many ZVDateTimePickers or DBZVDateTimePickers in your project, I created a tool which helps replacing all these old "ZV" controls with new DateTimeCtrls - it is attached to this forum post:  (you have to be logged in the forum to see attachement!).