Word! Glad you'll give it a try. :)
To answer your question rule 6 means we at the IFC are not responsible for any tax issues that you have with collecting prize money or when it comes to buying or selling in our Marketplace. It's up to you the individual to keep track of and pay any taxes you may have depending upon the tax laws of where ever in the world you live.
Hope that answers your question and if you have any more questions please feel free to ask and I'll do my best to answer!