I had an appointment for a 3rd (booster) vaccination at this place this morning, along with a friend who was accepted without question as a walk-in.
It wasn't busy, the guards and medical staff were super helpful, everything was well organized and efficient.
We were out in less than 50 minutes.
Required docs were passport or Thai ID card (not sure if the pink card was accepted), previous vaccination certificate either paper copy or on your phone - first timers would need to fill out extra forms.
Vaccines available were Sinovac for first timers only, those needing boosters could choose between Pfizer or AZ.
Free service under the government scheme.