I saw your other thread too KasaneTeto.
To be sure that you understand, usts can be 'made' for a certain voicebank but it doesn't mean others can't play it, although, since you downloaded Teto's triphone bank, you'll probably need to convert the notes inside to triphones; especially if it was a vsq in the first place as those do not convert into VCV (triphone) notes. That's probably why you found you could only play files 'made for Teto'.
After Importing the vsq into UTAU, to save it as a ust just click save or save as, if that was your question. If it was to actually export the vocals, do what Jpegurl described or go to Project>Render Wav File.