Legal Question in Civil Rights Law in Indiana

You misunderstand how the law works. The US Constitution permits states to pass laws that deal with certain matters. They can pass state laws on a wide array of matters, including whether one needs a license to sell some things in their state, or to have a business in their state. Not all states have the same laws. Cities and towns pass ordinances which are laws. Some deal with someone who sells door to door products. So, the issue is not that federal law is supreme. It is. But the issue is whether or not a state or city passes laws that are permitted under the constitution. Typically, all states pass some kinds of laws and regulations dealing with commerce within their state. What they cannot do is usurp the federal government's laws or pass laws that contradict the federal laws. They can, and often do, pass laws that mirror the federal government's requirements on certain issues.