Hi,
Hard to say without seeing the exact error from your build. Could you paste the build log / error output here?
In the meantime, a few things to double-check for AB32VG1 + RT-Thread:
Toolchain path is set correctly (RISC-V GCC)
BSP matches the board version
Environment (Env tool / menuconfig) is initialized properly
No missing packages after pkgs --update
See Ya,
Snow Rider