This is helpful and thank you for reaching out to them. Their response is vague enough that I guess it depends what you asked them. Proper citation on our “Contributors” page on the wiki is doable, but we can’t guarantee the comprehensive attribution that, say, ArcGIS maps tend to display in the corner.
Every state probably has slightly different expectations. To save you some time, state DOTs in several states like Massachusetts, Ohio, and California have already released their GIS layers into the public domain. I don’t know if we have a list somewhere that keeps track of these things, but you can often figure out existing permissions by searching the wiki for previous import proposals from DOT sources.