Cannot get Orca to work with the SDL example

All I see is

This example has no visible GUI, and a keyboard interface:
- [Tab] switches focus between two logical buttons.
- [Space] 'presses' the button, adding static text in a live region announcing that it was pressed.
Enable Orca with [Super]+[Alt]+[S].

Orca is turned on, but it won't read anything from this window. Does anyone else have this issue? I'm using accesskit_c v0.6.2. I also tried compiling accesskit from source, which worked after modifying Cargo.toml to not use winit but unix instead. I couldn't build the C bindings though. It requires rustup for some reason, but I want to stick with my distro's toolchain. I just used the header from 0.6.2.
The way I compiled the SDL example is as follows:

gcc -laccesskit -lSDL2 -I/usr/include/SDL2 hello_world.c

CMake again refuses to compile it correctly because it cannot find accesskit despite it being on my system, hence the manual gcc invocation.

Start with hello_world.c and the SDL example entry point, then inspect Cargo.toml and the CMake configuration around accesskit and its C bindings. Reproduce the reported accesskit_c v0.6.2 setup with Orca and the distro toolchain; done means the example builds and Orca reads its live-region output.