A few recommendations:
- Make sure the game window is active (ctrl+tab to check or click on the window), inputs will not work if the window is not active.
- This screen uses the arrow keys to move the mouse cursor and does not use the actual mouse. You can then navigate to the username bar (the cursor will change to a hand) and press confirm to continue.
Also note when the player name input screen opens, controls are Z - confirm, X - backspace, Arrow keys to move.
Hope this helps