Issue Using usgsdem()

I used usgsdems() function to locate which DEM file I need (see code below). It says I need 'washington-e'. Now I want to read in that DEM using usgsdem() and specifying my latitude and longitude ranges. However, whenever I run the code it opens up my folders and wants me to select a file? Aren't the DEMs built into the Mapping Toolbox? How do I extract my desired DEM data?

usgsdems([38.6694 38.7442], [-76.8792 -76.7124])
[Z,refvec] = usgsdem('washington-e',1,[38.6694 38.7442], [-76.8792 -76.7124]);