I don't know anything about him. But Beethoven set his 9th Symphony to his poem and Brahms wrote an choral piece to another one. I'm not arguing with that pedigree.Where and how should I start with Schiller as an English speaker?
If not by learning German then Coleridge‘s Wallenstein translations are the only instance I‘m aware of his having been adapted by somebody with talent. Which is odd considering how beloved he was by the English romantics and post-romantics. Carlyle did a biography of him and such.