Connecting Whiffle Doorbell to NVR

Hello Annke support team and community,

I just bought NVR 16CH POE (https://www.annke.com/products/4k-16ch-poe-nvr) with bunch of cameras, including a Whiffle Doorbell (https://www.annke.com/products/whiffle-doorbell-camera).

Regular IP POE cameras are working fine with NVR, but I can't figure out how to connect the Doorbell. It has separated app, which shows that the doorbell is working fine. I would like to have all recordings in my NVR ;)

Can someone give me a hint how to make it work?

Thank you in advance!