People who file a schedule C *are* in business and can get an EIN. It stands in as a redirect to their SSN for tax purposes. You don't have to have one to file a schedule C, but you can get one and it doesn't cost anything. Trendsource happens to require it, maybe because they see people with an EIN as being more committed to their business than people who don't. We don't really know why they want it. But if you want to work for them, you need it.
Time to build a bigger bridge.