Don't Panic: It Gets the Job Done
After reading these reviews, I was nervous that the adapter wouldn't work and jumped to that conclusion when I couldn't get the Adapter Brackets to click into place. While I'd inferred from the adapter's assembly instructions that I needed to remove the stroller's canopy, the trick is to remove the "plug" on the bottom hole of the stroller's Accessory Mounting Bracket on each side, as Kelly13 mentioned. I also found it helpful to unsnap the seat snap just above the stroller's Accessory Mounting Bracket on each side. From there, all went smoothly. Yes, this adapter works with the Chicco Fit 2 (which Baby Jogger's customer service had assured me, but which I had trouble finding confirmation of online), and yes, the stroller does fold with the adapter installed, though I'm still working out how to lock it in this configuration.
* This product review was collected by the manufacturer.