There are not any particular specifications required to take HDP Certified Administrator (HDPCA) exam. But it is suggested that your monitor have minimum resolution of 1600*900 to avoid the scoring of window during exam. You also need a webcam and good internet connection. It is advised to use the Innovative Exams compatibility check tool before starting exam at the following link.
And you are allowed to take HDP Certified Administrator (HDPCA) exam from the wherever you are.