Kinda hard to play detective across the internet with so few clues, but I'll try to contribute what I can.
Some background: Foreflight has historically tried to thwart interoperability. The original Stratus device was intended to only wotk with Foreflight, and vice versa. There were even several Stratus firmware updates and Foreflight software changes that intentionally broke compatibility with 3rd-party software trying to use the original Stratus. (The open-source "Stratux" project was designed to reverse-engineer the Stratus and provide a similar-functionality device that would work with any EFB app, not just Foreflight.)
All that is just to say that there's a history there of them intentionally making things difficult for non-Foreflight users to use Stratus. (And I'm not an expert in the multiple Stratus v1 firmware versions, so I don't know what the capabilities/limitations are of a Stratus v1 to work with iFly, and whether it depends on what firmware version it runs. Nor do I know how likely an original Stratus v1 might still be in use...they're pretty old now.)
The Stratus 3 was a pretty popular (and relatively recent) device, and just playing the odds, if you're saying there's a "Stratus" in your club plane, my guess (and it's just a guess!) is that's what it is. While the Stratus 3 *can* and *does* play with iFly, there's an internal setting that must be configured to allow it to do so...and I think it will toggle back to the "doesn't work with iFly" setting the next time someone with Foreflight connects to it, so if you're dealing with a club plane then it's probably something you have to deal with almost every time you fly.
You have to set the Stratus 3 to "Open ADS-B" mode.
Unfortunately, you need to have software to do that. One app that can do it is Stratus' "Horizon Pro" software...but that only runs on iPads. If you're using an Android device, it's trickier...I'm pretty sure there's software that can do it, but someone else who has done it will need to pipe up.
tl;dr: *IF* the ADS-B device in the plane is a Stratus 3, you'll need to figure out how to switch it to "Open ADS-B" mode before iFly will connect. You can use the Stratus Horizon Pro app if you have an iPad, or hopefully someone else can suggest a different app if you use Android. (If the ADS-B device is something other than a Stratus 3, then talk to your club officers and get more details on it, then come back and let us know.)