I played around with the form. This is what you need to fill in:
FFF is the first name, MMM the middle name ( optional), AAA the last name.
Thailand is probably still not in the list of countries of residence.
Filling in accomodation information was a challenge, since Pattaya is not a province nor a district nor a subdistrict and you must choose those things from a list.
I didnt click on Submit, but everything else worked. When you type something in a list, it can take some time until the list shows the possible choices.
If you stayed in certain countries (like Colombia) within 14 days before arrival, you have to upload a proof of yellow fever vaccination.