Theorbo as instrument

I ma using 14 course baroque Theorbo as the instrument on an empty project and I get a g-clef sheet. A theorbo barely goes that high. I need an f-clef. And, when I manually change the clef to f, the playback is not able to play most of the notes.

What kind of theorbo did they have in mind?

Welcome to the forum, @kbayegan. The sound library included with Dorico does not, I’m afraid, include a dedicated theorbo instrument. One of our partners, Cinematique Instruments, makes a lute instrument that you could use with Dorico (information here), and there are other third-party sampled instruments that you could use with the software.