Trouble Signing In - Dire Call for Help

So I’m new to volumio and I currently have a Raspberry Pi 3 Model B, and when i boot it up after flashing it, i’m prompted with Under-voltage detected! (0x00050005). I can still input the login, but when i press enter to get to the password line, I can’t input anything.

What login?
Just use a browser or the app on your phone to manage it and finish the setup.
But it sounds like you may need a better powewr supply for it.

the login where i put the password on the initial bootup of the pi, where it’s all black where it gives you the option to input the username and password of volumino

Volumio is designed to work headless. It means you need to connect to it from a other device on the same network from a webbrowser.
see howto