Detection of Bridge and devices that are part of a existing Philips Hue network

How to set up diyHue running on a Raspberry Pi so that it recognizes an Origial Philips Bridge with its connected devices. I use, as suggested , the Hue Essentials app on an iPhone.
Pi is initiated with NOOBS and diyHue is installed using the automated install procedure.
The app sees the diyHue/Rapberry bridge, I can pair with the app, however don’t see the devices on the Philips network. Feels like I’m missing a working link between the 2 bridges.
Update: Followed the procedure to connect as mentioned under “Hue Bridge Lights” in the manual, so see all my lights now, was hoping to see all devices as well…was looking for the motion sensors.
Is installing a ZigBee dongle to the Raspberry Pi the only alternative?

Glad you got your lights working. I’m pretty sure the only way to get your sensors working is with a ZigBee dongle, but @mariusmotea is the best one to confirm that.

My learning curve I suppose. Coming from a diverse situation with multiple technologies (KaKu, Plugwise (Zigbee HA compatible), Somfy, Hue), I decided to standardize

The original Bridge does not expose the Sensors and Remotes to the Hue API. As far as i know, the only way is with a seperate Zigbee Transceiver as cheesemarathon said. Conbee or Conbee 2 by Dresden Elektronik is supported at the moment.

Thanks a lot, I will order a Combee, although I do wonder how apps like e.g. Hue Essentials do get sensor/motion information out of the original Hue Bridge when
paired directly with that bridge.

Best Regards Cor

Registered as a dev at the Hue site. This gives me access to the API description for the Philips/Signify Hue bridge. Sensors, including the motion sensor are described in there.