Took me a couple tries but you need to do the following.
1. download "Webster1913.001.zip"
2. download "Webster1913.002.zip"
3. download and install
7-zip
4. rename "Webster1913.001.zip" to "Webster1913.zip.001"
5. rename "Webster1913.002.zip" to ""Webster1913.zip.002"
6. Right-click on "Webster1913.zip.001" and select "7-zip->Extract to Webster1913\"
7-zip will find both files and combine and unzip them. 7-zip and renaming are
required for this to work. This will result in /Webster1913/Webster1913.prc.