Which systems are you interested in? Are you looking for some particular ideas or the entire system?
It happens that most of the systems that are in free access are well-known, so they could be not so interesting.
The best thing you can do is to create your own collection of systems, analyse the ideas they are based on and then create something own. For example, there is an interesting resource on indicators-based strategies here. As they are not “gurus” teaching trading, they could show a bit more details. You can also search like “Forex strategy” and find dozens of them, but keep in mind you will need to make an extract and create something own because almost all available free strategies do not work any more.