From client perspective, there is almost no difference between cloud and server aside connection workflow. I theory you can use same app with server and cloud.
Plugin may require some adjustments to work with Photon Server. We did not test it because server is advanced topic and we hardly find many Construct2 users who want invest in server development. So cloud is our priority. Chat can be implemented easily with plugin and Photon cloud.
If you want try server, download Photon js client sdk https://www.photonengine.com/Download/P ... -0-0-2.zip
(or other sdk of your choice) and connect to local master server instead of cloud's nameserver