There is a known bug, in which npm does not install module dependencies. A workaround is to explicitly list them as top-level dependencies. Here is a script that transfers dependencies from aurelia.json into package.json.

PS> $obj = Get-Content aurelia_project/aurelia.json | ConvertFrom-JSON

PS> $obj.build.bundles | `
Select-Object -ExpandProperty dependencies | `
ForEach-Object { if($_ -is [System.String]) { $_ } else { $_.Name } } | `
ForEach-Object { npm install $_ --save }