Incomplete instructions and build issues

Trying to compile following the README.md, I can into the following problems:

• The git clone command shows the use of the SSH protocol. This results in a git@github.com: permission denied (publickey) error for me. Using git clone https://github.com/rive-app/rive-renderer works.
• Using git clone --resurve-submodules https://... fails with the same error. Changing .gitmodules to url = https://github.com/rive-app/rive-cpp.git and then running git submodule update --init --recursive helped.
• The Build GLFW step requires CMake. A standard Xcode installation does not come with a bundled CMake (at least not in v12.4), it needs to be installed separately and added to the PATH to avoid ./make_glfw.sh: line 24: cmake: command not found
• The Call Premake & Build step doesn't mention at what path to run the commands. It can be deduced that it must be the rive-renderer folder, though.
• Running the ... premake5 gmake2 ... command fails with Error: ...renderer/submodules/rive-cpp/build/rive_build_config.lua:323: attempts to concatenate a nil value (global 'iphoneos_sysroot'). I'm not familiar enough with Lua/premake but it seems strange that the code where the concatenation happens is executed despite filter({ 'system:ios', ... }). I worked around the problem by adding or '' in build/rive_build_config.lua where the sysroot variables are set.
• path_fiddle is in the rive_renderer folder, not in out/release.
• The metal utility is required, which means you need a full Xcode installation, not only the Command Line Tools for Xcode. I can't install Xcode on the device in question and I'm not even sure if the latest available Xcode for the outdated platform includes the metal utility so I cannot check for more issues with the compilation.

The system I tried the above on was a MacBook Air from 2014 running Catalina, Intel CPU. This may not be a representative device but I think all of the above papercuts equally apply to newer devices and OS versions.

On Windows, the first two bullet points apply as well. Other issues I encountered:

• To run make make_glfw.sh, you can use Git Bash. But it doesn't have the touch command which is used in renderer/shaders/Makefile. I substituted @touch $(MINIFY_STAMP) with echo "" > $(MINIFY_STAMP).
• The premake command needs to be different to use the Microsoft toolchain. The environment variable needs to be set differently - I used $Env:PREMAKE_PATH="C:/<some-path>/submodules/rive-cpp/build" in PowerShell. The generator needs to be set according to the installed Visual Studio version, e.g. premake5 vs2019 --toolset msc ... instead of premake gmake2 ....
• There were issues with the path_fiddle target that I worked around by setting the C++ standard to C++20 and disabling to treat warnings as errors (/WX-) in Visual Studio for the rive.sln. Using vcvars64.bat, everything compiled successfully with msbuild .\rive.sln and the path_fiddle.exe works.

I'd appreciate it if you could share the commands you use to compile for Windows. Do you use MinGW?

Review README.md and the referenced .gitmodules, make_glfw.sh, renderer/shaders/Makefile, and build/rive_build_config.lua. Reproduce the documented macOS and Windows build steps, then update the instructions with prerequisites, paths, commands, and platform-specific workarounds. Done means a newcomer can follow the README and reach a successful build on each supported platform.