You can install the mounting kit on either side of the ORS (bottom or top side), and you can install them in either way as shown on the picture depending on what spacing works best for your case.

Use mounting brackets to secure the ORS on the pole.

It is very important that the ORS is installed vertically with the connectors facing towards the ground to ensure it stays waterproof

It is likely you will need the ORS to be plugged to GPS for GPS synchronization, so make sure to plug the GPS antenna as well. Please check your GPS antenna specification to see what direction it should be facing, generally it should be facing up since GPS signal is coming from above.

Install the antennas on the pole. It is very important that the antennas be properly oriented for the range not to be decreased. Please check this page for more information: What is the radio range of the ORS ?