CAMWorks don't directly charge for all their post processors. The resellers sometimes charge for them, based off of the number of hours the put into writing and developing the posts. Some posts take hundreds of hours to write, so they offset the costs of development time to selling some of the posts.
It sounds like to me your reseller gave the wrong post either that, they gave you a post that was intended for a Haas but didn't update the name in it the source files.
However, I do not believe that either of these are your issue. When the "diameter" of the endmill is defined on the machine, the machine will typically then offset the XY values it reads from the post by the tool radius. CAMWorks has the option to offset those posted XY values by the tool radius or not. I am speculating that this option is being offset by both CAMWorks and your machine. You only need one or the other to do it. This can be achieved by not entering a tool diameter (maybe a zero diameter) on the machine or when within the CAMWorks Contour Operation, go to the NC tab. There is the option to turn on or off toolpath center compensation. I am guessing you have this on... this means CAMWorks is offsetting the XY values for you. Turn this off and then it won't do that. (Basically draw a simple square, post it. change that option and post again. you will see the difference in the posted XY values).