hello i want to use poe port for my Ubiquity PowerBeam AC 500, can anyone guide me for this one ?

T.I.A

if that accepts passive PoE then RB260/RB260GSP or RB750UP will work.

At least the Nanobridge, Rockets and Airview cameras work. Since that device needs 24V 0.5A gigabit passive Poe using the same standards, it should work as long as you provide the necessary 24 voltage to your Mikrotik device. Remember, the PoE output voltage is about 0.7V smaller that that of your power supply...
A RB260GSP using the supplied power adapter should do.