Just a word of warning...
We have a similar building at work for storing our pallets out of the weather. It is anchor bolted to the ground and was professionally installed.... it did fine for about 2 months. Now the frame is bent and has a serious lean to it, some of these low cost places use sub par metal. The framing is super thin and bends/twists very easily, especially if you have mild wind in your area.
I'm sure if you used additional bracing would be fine, but just wanted to let you know my experience with these shops.