ERA contains different "modules" that can be accessed in any device.
You just need a Windows, Mac or Linux computer to start the "server".
Then you can use that same computer, another one, or your WiFi to connect from any smartphone or tablet.
The character status module is specifically designed to be used during the adventure in the players smartphones or tablets.
The other modules require more stuff on screen, but you might try them on a 10'' tablet if you like. One of my players has been known to use the character sheet module to level up in a 7'' tablet.
I am not sure if that answers your question, let me know if I misinterpreted it.