The create command needs to go before all the other commands.
Also, you placed the overlay in zone 2 but haven’t cut to zone 2.
INT. WALKINCLOSET - DAY
@overlay AMBULANCE create text |color:white, underline , outline:white| Welcome
@overlay AMBULANCE shifts to 86 425 in zone 2
@overlay AMBULANCE scales to 2.818 2.818
@overlay AMBULANCE opacity 1 in 0