We pressed to buy 2 museum tickets from the Traveloka app for about 660 baht, but bought them during the promotion period and got a 200 baht discount. It was really worth buying tickets through Traveloka this time.
When we arrived, we left our bags in the locker. We could leave them for free. Then, we opened the QR code screen and scanned it on the machine. When the transmitter responded, we could go into the museum. There was no time wasted and we didn't have to exchange for a physical ticket. However, we had to enter through the door that said "for online e-tickets only."