Apparently, this does not apply to the Pranburi office. In December 2022, you could show up without an appointment to get a Thai driving licence based on an international driving licence, whereas now in January 2023 you have to book an appointment in advance, otherwise they will just check your documents and make an appointment for later. Just today I was with someone to renew a Thai driving licence and overheard several people at other counters being asked for their "online booking confirmation". If they didn't have it, the officer would give them an appointment. So as long as the booking system works, I would rather play it safe and book in advance.
The e-Learning can be done here: https://www.dlt-elearning.com
And the appointment system can be found here: https://gecc.dlt.go.th/login