Do I power a stepper motor with 24V and Arduino?
There are 2 versions of the motor in the datasheet, which is liked in the O.P.:  +6V version and +24V version.  But the datasheet doesn't say what the markings on the motor are in either of the versions.  However, the datasheet tells what the DC resistance of the windings should be in each version (table on p.2).  8Ω for +6V version.  50Ω for +24V version.  If you measure the resistances of the windings, you'll be able to tell which version you've got.  This stepper is unipolar, so it should have a common connection.  Measure resistance between each winding and the common.