I do not have a 9350 and have a 9250. I have an Android tablet (easier to see than on small phone screen). The app in the Google Play Store was the over-all "smart home" app for all appliances.
Installation of the app specific to the vacuum was performed, I think, by the smart home app when registering the vacuum. It should know what version to install. The model number etc. is entered. See instructions in the manual. The registration involves entering the password for the router into the app so it can transmit the password to the robot so it is set up to connect to the router. Initially the phone or tablet connects directly to the robot, which gets the password and subsequently connects to the router. I am not an expert in these WiFi technicalities.
Some other 9350 users are on German Roboter-Forum. They have had difficulty with the WiFi connection, but I think on fancy routers with extra security features. They have loaded the app and run it some times.
I do not use the WiFi nor smartphones much for anything. Recently when trying the WiFi the Smart Home app starts with a message "you can now update the app", but when running reports there is no connection -- even though the tablet is connected. I think this means there is no update available at the remote server -- the server is not responding to this request specific to updating that particular app. The app for the vacuum installed still runs.
I think all the updates so far have involved only the communications functions and the app itself, not the robotic control firmware in the robot. The WiFi is a complex function with lots of supporting software in the robot.
Note in the vacuum app with the Smart Home, swiping to the side shows another page with settings and info for the app including version info. Within the vacuum app, there is a section at the bottom with info on the firmware version in the robot.