I do not have a Ring doorbell to test but managed to migrate the binding to OH3 and it installed properly in my instance. Let me know if it works for you -
In case it complains of missing json-simple dependency you can install it manually in karaf console -
bundle:install https://repo1.maven.org/maven2/com/googlecode/json-simple/json-simple/1.1.1/json-simple-1.1.1.jar