Can someone tell me how to start livesplit properly and it automatically stops when I get the gold coin machine in coin stamper?

Go right click on splits and click on settings and toggle global hot keys on, bind a key by clicking on the current key box and pressing the hot key you want. When you want to start your run, press the key and press it again to stop the timer

We don't have an autospliter, so you have to manually stop at the correct time.

thanks