Darhon Rees-Rohrbacher has an arrangement in The Liturgical Harpist, vol 1, in the Lenten Hymns section. It is arranged to be playable on lever, but there are a fair number of lever changes. I don’t know which harp your daughter plays. Most of her arrangements are fully Intermediate level; this one is somewhat easier. I think Afghan Press is now the distributor for these arrangements–and they are uniformly excellently well done.
Most everyone is familiar with J.S. Bach’s harmonization, which has altered harmony and equal rhythm, and I’m assuming that is the one you’re wanting. However, the original Hassler tune was half note/quarter note rhythm, with much simpler harmony. If you have an Episcopal Hymnal 1982, the original can be found at #169, and it is playable pretty much as written, probably with some damping needed. (Bach’s version is at #168 in that hymnal).
Charles Nix