Great selection of the Prodigy P3 # 90195 brake controller - definitely one of my favorites due to ease of use!
According to my research your 2021 Entegra Aspire is built on a Spartan chassis. While I imagine there are some wires either up under the dash near the steering column or underneath the driver's seat, there hasn't been any information released about a brake controller plug so you'll likely have to hardwire it in.
If you reach out to Entegra with your VIN they should be able... view full answer...