As previously mentioned by others, you'll need to build a new integration in Iris to fetch information from the file manager.

You could create a custom REST service that exposes an endpoint for your use case. The REST service would send a RPC request to the RPC Broker via a custom business operation. Furthermore, this business operation would handle the communication between Iris and the RPC Broker. This is required, because the RPC Broker does not support REST communication and instead relies on its own proprietary communication protocol.

We have created such business operation for Iris <-> RPC Broker communication. If you're interested, please feel free to PM me :)