For your weight and height, you will not need a lot of volume and width for stability. Length, however, will be very useful for paddling speed, important for exploring on flat water and gliding into the waves, so you can have fun on meek waves with nobody on them.
I'd say that this means about 120-140 liters in volume, 29" / 30" in width, and at least 10' in length. A sleek longboard or gun/cruiser shape.
You do not need to get an expensive board as a first one. If you have no previous surfing experience with hard boards, you will probably ding it a lot, it would be a waste to start with an expensive one. But big brands will resell better, and if you are attracted to a brand or shape or graphics, go with it, it is part of the experience.
In the Naish range, the Nalu 10'6" may be the closest choice. A tad too much volume, but it will paddle better. In SUPing, more is better than less.
www.naishsurfing.com/wp-content/uploads/2017/08/2018SUP_Board_Spec_Sheet_Final.pdfThere are of course plenty of choice in other brands, too.