I don't think it should be a problem. All of the mods and resource content have been available all over the internet for free, for years. We are just providing the same mods for free here. The only thing requiring payment is the rewrite of the engine, which was also provided over the internet for free, years ago. Our legal counsel has told us that if that source was given out for free, but was substantially rewritten like we did, we can charge for our rewrite.
We are not in violation of any laws, and this was legally vetted during a year-long process by our lawyers. If you have any concerns regarding such, you may contact our legal counsel: https://www.dubofflaw.com/