The translation sounds weird to me. Why isn't this "a lot of" experience / why not много?
I think literally translated "a lot of" is "много", but in the usage of this sentence it should be "большой". I think the translation should be corrected to "Do you have a lot of professional experience?"
I wrote "У вас большой профессиональный опыт?", but it wasn't allowed.
I did the same and I'm a native Russian speaker, so that was confusing..