There are a number of ways to make that connection, just about all of which will involve some degree of metal fabrication. Too many options and with no pictures it is pretty hard to see what's going on. Your post anchorage idea would probably work but hopefully you have a professional engineer doing uplift (wind) calcs for you to make sure. Footing size? Can we assume that there is a plan that the contractor is supposed to follow? Hopefully you've made sure he's pulling a permit so the inspector can advocate for you in the event that something is done poorly.