I have a browser-based project and used the limited rewards feature to allow people to name in-game items and gain access to a downloadable certificate.

Now I would like to add some more downloadable files to the project that are available to anyone, but I don't want anyone else to be able to download the certificate. I'm confused about whether this is possible to set up or not. I have the project price set to "$0 or donate" and "New purchases and downloads require a reward." When I upload a new file, I see there's an option to "Set a different price for this file" but I'm unclear on how all these things interact.

Is what I'm trying to do possible under the current system?