Is it safe for me to use my ACUdraw or ACUdraw PRO without engaging the pawl lever?

No.  Before cranking your ACUdraw PRO or ACUdraw, engage the safety pawl and make certain the string-claw is securely seated on the bowstring.  Otherwise, you may lose control of the crank handle, dry-fire the crossbow and/or send the crank handle spinning out of control.  Failure to heed this warning may cause serious personal injury and/or property damage.