Tateyama Kurobe Advance Reservation Ticket

I want to buy an advance ticket of the Toyama to Ogizawa route from their webstie (https://tateyama-kurobe-webservice.jp/AlpenTour/html/VW001W0010.html). However, I realized that we need to choose an exact departing time from Tateyama station onwards.

My question isc If we arrived a bit late at Tateyama station, and unfortunately late for the reserved time ticket. Can we still join the next train? (In other words, do we have to stick to the reserved time we have chosen when booking the reserved ticket, or can we use this reserved ticket at any time during that day?)

I am also planning to stay one night at Murodo and will proceed to go back down to Ogizawa station the next morning. Can I still use the same one-way ticket the next day going down from Murodo station?

Thank you.

u can go nagano eki higashiguchi to ogizawae ki by Alpico kotsu bus,3100 yen,105 minutes