What Covid insurance documentation do my parents need for entry into Thailand?

I’m hoping to get some help on the Covid insurance required to enter Thailand. My parents are from the USA and have Kaiser insurance. They are coming to Thailand in April. They called Kaiser and explained that they needed to show proof of Covid insurance with at least $20,000 coverage (but maybe it’s $50,000 because some websites say $20k and some say $50k... it's confusing). Kaiser said they are fully covered outside of the USA for accidents as well as Covid-19 treatment and this document is what Kaiser sent them back. I’m pretty sure this won’t work, since it doesn’t show any numbers of the coverage amounts. Am I correct, and if so is there any specific name for the document they need to show that we can ask Kaiser for? Also, the Kaiser paper says if my parents require Covid treatment in Thailand, they will need to pay for the treatment themselves and then file a reimbursement claim. I’m thinking that might not be the type of insurance that’s required to enter Thailand. If someone could please help clear up some of this we would really appreciate it!