Click on a red block on the map and then download to save the vector contours. Contours are in zipped geodatabases that range from 1GB to 2.8GBs in size.
The 2016 Contour map service (in the Elevation category) may be easier to use depending on your application.
The contours were created from the 2016 statewide lidar. Each zipped file for download contains a geodatabase and a metadata xml file.