Can I put a Book now button in the tour's menu bar?

Yes, you can by filling in the menu bar's call-to-action button: on the Design tab (in the Advanced view), open Top nav bar – multi menu, then the Menu tab, and in the card Call-to-action button type the Button label (up to 60 characters, such as Book now or Reserve a table) and the Button link, then Save & Render.

The button sits at the right end of the menu bar, so it shows in every room, and on a phone at the bottom of the menu panel. It shows only when both fields are filled and the menu bar is shown. An http or https link opens in a new tab. The label is one language: it does not follow the language a visitor picks. For a button in one room only, use an External Web Link hotspot instead: Add a call-to-action button to a tour compares them.