The reason why it is asking for a password is because you are trying to open a passworded quest.

I don't remember exactly because I use Pure, (and I really don't like the BS set) but to get the BS graphics for your quest you can open up examplebs1st.qst (because that one shouldn't have a password) and then export the graphics pack, or the tileset or whatever.

Start up a new project, then import your graphics pack or tileset or whatever, and then you will have BS graphics.