Certified GKH Gardening Expert
Unfortunately, these are only hardy to zones 9 and up. They won't require a winter dormancy. They need to be kept at no lower than 60 degrees to grow healthily. The best plan of action would be to grow it indoors during this time. Place it in a Sunny location. It is best to be on the south side with a south facing window, if that is possible.
Here is an article with more information: https://www.gardeningknowhow.com/ornamental/vines/mandevilla/winterizing-mandevillas.htm