Thanks @jreneew2! I tried downloading the file you linked, but I should have also said that I’m on a mac right now. I think I need the JSON files for the libraries, not the source files. I read on this page that
For C++ and Java a JSON file describing the vendor library is installed on your system to C:\Users\Public\frcYYYY\vendordeps. This can either be done by an offline installer or the file can be fetched from an online location using the menu item in VSCode. This file is then used from VS Code to add to the library to each individual project. Vendor library information is managed on a per-project basis to make sure that a project is always pointing to a consistent version of a given vendor library. The libraries themselves are placed in the Maven cache at C:\Users\Public\frcYYYY\maven. Vendors can place a local copy here with an offline installer (recommended) or require users to be online for an initial build to fetch the library from a remote Maven location.
Also on the Kawai Labs page, they wrote that
At this point, the “navx_frc.json” file will be added to the “vendordeps” directory in your project. This file provides GradleRIO with all the information need to compile and link your application with the navX_FRC libraries – and even enables you to debug into the navX_FRC libraries if you wish.