It's worth knowing that, if you are from RoW, and you apply for temporary admission to the US, usually when you are on holiday and filling in the green card before entry, not only do you have to declare that you were not complicit in the persecution of Jews from 1939-45, and that you have not recently been on a farm, and that you are not entering the US in order to work or to seek employment, you are not allowed to take up vocational training which might equip you to seek employment in the US.
One of my chums was sternly told by US immigration that he would not be allowed during his visit to go to, for example, evening classes in, say, floristry, in case it equipped him to take a job as a florist, thus putting a US citizen who might otherwise have taken that job, out of work.
I am no expert on US immigration laws, but they are quite different from European laws. I notice that none of the posts advertising this audition company claim to be from a person outside US, or have any experience of visa requirements. I have only been to the US on holiday, when there is a concession on visas. It would be interesting to hear from a European who has travelled with the intention of paying for training as an actor.