Dry Acid vs. Muriatic Acid

Per Leslie's Water Analysis Report, my ph was 8 and my TA was 130. Thus, I was told to buy and put in 2lbs. 6 oz. of Dry Acid for my 19,800 gallon fiberglass pool that uses a salt chlorinator. I told them I would rather use Muriatic Acid as it is much cheaper. They said Muriatic Acid should not be used on fiberglass pools. Can I use Muriatic Acid? If so, how do I convert the dry acid to the muriatic acid?

Thanks!