Since I cannot guess the error message, I’ll assume it cannot find the file. Assuming the file is in the \Files\ folder:
Add-AppPackage -path "$dirFiles\Shapr3D.Package_5.520.6157.0_x64_ARM64.msixbundle"
If you want to try to log what is happening with this command while in PSADT, try this:
Add-AppPackage -path "$dirFiles\Shapr3D.Package_5.520.6157.0_x64_ARM64.msixbundle" -Verbose *>&1 | Out-String | write-log
If the logging doesn’t work, look here for other logging methods: