On the upper right corner of the Editor interface, there is a button to start the run mode, or you can use the shortcut key F5 to begin.
By clicking the ▶ (start) button, the scene will enter test mode.
After loading, the simulation of the scene will begin, and a virtual character will be generated at the spawn point.
The WASD keys (or the arrow keys ↑←↓→) will correspond to the character's movement controls, and the spacebar will control the player's jump.