It's not a client, this is a launcher.
Don't confuse them.
Client - is the Roblox application itself and its game files.
Launcher - is a program that allows you to launch game client.
This launcher has 2008M, 2013L, 2014M, 2015L, 2016L, 2017M, 2018E-L, 2020L, 2021E and 2022M clients.