That law is in place to prevent another "Red River Rebellion", not to stop people from shooting each other with plastic on the weekends.
As Ricochet said, you would have to be seen as a threat to the public order to get on anyone's radar.
I would caution you against "joining a team" right from the get go. That's not necessary to get into the sport, and on the contrary can actually pigeonhole you into buying gear you don't really want, or restrict your ability to attend events.
There are awesome teams out there, in fact most are. But you need time to learn the sport and get to know the local players in your area BEFORE you get on a team. Any team that blindly accepts new players without getting to know them first is a GIANT alarm bell.
Get out there and sling some plastic, it's all good.