Answer by Straw for NPM install doesn't work from behind our proxy which requires authentication - tried config set proxy=

Try to add double quote to your commands :

NPM CONFIG SET PROXY = "http://<domain>%5C<username>:<passwordwith#>@ddcrpit311v1.corp.<company>.global:8080"

and :

NPM CONFIG SET HTTPS-PROXY = "http://<domain>%5C<username>:<passwordwith#>@ddcrpit311v1.corp.<company>.global:8080"

This has worked for me. ;)