Ask HN: How do you deal with unresponsive freelancers?

I run a very small game studio and we have contracted the help of a freelancer to help with some marketing and some creatively-related jobs. They are fairly well known in the industry and eagerly agreed to help promote our project, asking us to forward the paperwork to sign. It has been 5 days past the deadline we asked for the paperwork (nda, contract) to be completed. Is it unreasonable to suspect they might be ghosting us? If so, what's the best course of action since we only communicate through email?