Is the app available in Europe or in the Google Play store? Will phones be able to handle 300kbit/s network speed in case an automatic update is running or an app is trying to download something?
"Handle" what exactly?
If your phone downloads data, it will consume those 300kbit/s
Android Devices with Android 7.0 or higher should have a "Data Saver" feature (check buttons in Notification area) which can limit data-traffic to foreground apps, in case you want to reduce the amount of "data vampires". Especially helpful when abroad...