A multi user booking calendar website and/or app

I want an app that will be used for travel agents or tourists to find available guides at any time they want. =================== VISITOR INTERFACE: TOUR DATE(S), REQUESTED LANGUAGE, AREA/CITY TO BE VISITED ( multi-select dropdown menu) sections are necessary in a simple search page. ==================== TOUR GUIDE INTERFACE: A CALENDAR - This calendar will be fully booked or marked red "as default." If tour guides want to open availability, they will turn available dates green. Also, on every available date, they need to fill a form that contains: LANGUAGE THEY SPEAK, CITY THEY LIVE, AREA/CITY THEY WOULD LIKE TO GUIDE (with almost 100 options as a multi-select dropdown menu.) This form should have options like "Save as default or apply default settings." A PROFILE PAGE Photo, Privacy and Contact options, Password and maybe that dropdown menu details mentioned above. Up to 15.000 tour guides will register this app/website. They will register with their real names, but their name will be public like "Alex B. or John C.". Registrations must be under control always. We don't want unlicensed people to register like a guide. So there must be a "review" period for every registration. For communication between guides and customers, if we can provide a whatsapp, telegram or email bot, it will be great for privacy. I am open to new ideas about that. Monetizing this app is not my intention, but I am still open to reasonable ideas. I tried to explain what I want as much as possible. It is basically a booking calendar site that 15.000 people can set and share their available dates. Looking forward to see your offers. Thank you.