Ah, my friend, you have fallen into the marketing trap. What you have there is the hopped extract for a Mexican cerveza, but not the yeast. The yeast supplied with the kit is a dried yeast that probably attenuates more than your typical ale yeast, but does so at ale temperatures (think California Common yeast). If you ferment with the supplied yeast, you will get something close to a cerveza, but not spot on. Opt for the real liquid lager strains and build your starter at the lower recommended temperatures of 40-50 F in a 4 liter starter for a 5 gallon batch, if you have the capability of fermenting at those temperatures. Otherwise, ferment as the kit instructs and cross your fingers. I don't think you'll be disappointed either way.