Running ./Build.cmd debug says Unable to load script

[ImaginaryDevelopment]

I was able to run a simple ReactNative App per https://reactnative.dev/docs/environment-setup
linked from https://reactnative.dev/docs/getting-started which the docs here say to use.

Android Studio is installed and I followed

adb devices -> emulator-5554 device
yarn -v -> 1.12.3
node -v -> v15.10.0
ANDROID_HOME=C:\Users\username\AppData\Local\Android\Sdk
Windows 10 Home
dotnet --list-sdks does not show anything starting with 3.x but I do have 5.0.200
but the emulator shows this when I try to run a fresh pull of this on master