Part 107 UAS crew reported a near miss with a manned aircraft while operating in controlled airspace with an airspace authorization.

Narrative

Date: DayTime: Approx. XC:36 am localPlace: ZZZFAA Part 107 Airspace Authorization: XXXX-XXXX-XXX-XXXXX We were documenting flight test at ZZZ all morning. A call to the Tower was made via telephone the day prior and when we arrived on site; to advise the Tower of our UAS operating location and intentions for the entirety of the day. We started the day off on the Eastside of [Runway] XXL/XYR in Zone X as defined in the Airspace Authorization. Somewhere between XA:30 and XB:00am we called the Tower via phone to inform them of our new operating location: Just West of [Runway] XXL/XYR in Zone Y which is north of [Runway] XZ/XA.Remote Pilot In-Command (RPIC) called ATCT on Tower frequency (approx.. XC:34am) to request permission for liftoff just a few seconds after the Tower gave clearance to Aircraft Y to take the runway. Tower responded with 'approved'. The Remote Pilot (RP) started props; lifted off and flew the UAS north of the liftoff location to approximately 220 ft AGL to film the takeoff of Aircraft Y. The RPIC (acting as the Visual Observer (VO)) was monitor tower frequency; scanning for other air traffic and watching the position of the UAS itself. As Aircraft Y was started their takeoff roll the RPIC heard Tower call Aircraft Z. The RPIC does not remember what was stated but within seconds he heard an airplane approaching from the south. RPIC spotted the intruder plane and called 'Descend; descend; descend.' The RP starting maneuvering UAS and spotted the intruder aircraft flying very close to our vehicle. The RP stated that it 'appeared' that the airplane was below the drone by less than 50 ft. The RP returned the UAS back to the liftoff location and landed. RPIC called the Tower via phone and reported the incident.