Saudi Aramco Facilities Fires, page-47

At this point in time I have no information on the types of drones used.

For the cheap toy like drones to work in the current circumstance would have been launched nearby and to be guided to a precise target point (a point of known vulnerability) by someone close by.

Iran has a wide inventory of drones ranging from toy-like devices to clones of US designed stealth drones to UAVs capable of launching guided surface to ground missiles, as depicted below.

If more sophisticated drones were used the finger to Iran get pointed.