No problem! You need to install Flashpoint first and then the games (and platforms) you want. I haven't tried it in a couple of years, and don't have it currently installed (it does require quite a lot of disk space), so I don't really remember exactly how it was. They have a FAQ you should probably check out: https://flashpointarchive.org/faq
I think you should give it a go if you're really into playing WJ, or if you're interested in playing other old Unity3D/Flash games too. The catalog is massive.