Den, the FIRST sentence is correct. I' ll explain why. There's a formula: If you use it as " I'm worried about", you have to use the clause sentence"that I won't receive 100$". If you use just "I worry", then your sentence will be like this: " I worry about not receiving 100$". See the difference?

Я просто обеспокоен, тем что я не получу 100 долларов. ИЛИ я просто волнуюсь что не получу 100 долларов.