In 2016 I applied and received my OA visa issued in the USA.
I took the disease check off list to my doctor. He had me take the TB test which I passed. He sighed off on the others.
Medical insurance was not required at that time. Now it is. I had insurance but not from an approved Thai company. A reliable agent helped circumvent that requirement for annual extensions. For a fee, of course.
Today I would recommend anyone thinking of an OA to just obtain a non immigrant O. Currently no insurance requirement.
Since then I have obtained a LTR VISA. My insurance is approved for LTR but not OA. Strange but true. TIT.