Why the mobile site is usually handier than the app
Because there is nothing to download, update or hide from a store. The Riobet site is responsive: the layout adjusts itself to the screen width, the buttons grow bigger for your thumb, the catalogue folds into a single column. You go in on a normal link through Chrome, Safari or any other browser - and you get the same account, the same balance and the same cashier as on a computer. 24/7 live chat support and the catalogue from 90+ providers are right there too, with no separate install.
The app is that same shop window packed into an icon on your home screen. The main plus: one-tap launch and push notifications about bonuses. The main minus: you still have to get it from somewhere. In the App Store and Google Play the online-casino category is restricted, so official clients there come and go. By Russian-language accounts, Riobet has builds for Android (an APK from the site) and an iOS option, but availability and how you install it both change. Do not take reviews at their word - check the download section on the operator's own site.
Android: only install the APK from the official site
On Android the casino usually hands you the APK file directly - that is normal practice for a category Google Play will not allow. The file downloads from the "Mobile version" or "App" section on the site. Before you install, Android will ask you to allow installs from an unknown source for that specific browser - a one-time permission.
And here is where the risk hides. An APK from search, from someone else's Telegram channel or from a forum is a lottery you are better off skipping: it is easy to pass off malware that steals passwords as the Riobet client. The rule is simple: a link to the APK comes only from the operator's page. If it is not there, then there is no Android build right now, and the mobile site covers the same job.
iPhone and iPad: Safari is usually enough
On iOS Apple keeps casino apps on an even tighter leash, so there may be no separate client at all. The working solution for an iPhone is to open the site in Safari and add it to the home screen: the icon shows up next to your apps and launches full-screen, almost like a native program. That gives you the convenience of an app with no install and no dependence on whether Apple lets a client into the store.
What eats data and battery on a phone
The heaviest are live casino and crash games: that is a video stream and a constant connection. Ordinary slots are lighter, and most load once and then spin locally. If you play on mobile data, keep three things in mind: a stable connection matters more than speed, a deposit from 10 $/€ goes through the same on a phone as on a PC, and a crypto withdrawal on a phone is just as fast - around 5-10 min. To save charge, close background tabs and switch on battery-saver mode.