That's a great question! Unfortunately, what you're looking at is actually tablature for a mountain dulcimer, which is a strummed instrument that has frets and just a few strings. So the 0 would indicate an open string, and the 1 would indicate to press down at the first fret, etc. Unfortunately, that notation doesn't really apply to the hammered dulcimer.
There are people who have designed different systems of notation specifically for hammered dulcimer, and maybe someone else can chime in if they know of any examples!