Typically when you get errors like
The name 'nr' does not exist in the current context , it means that the specific resource is not present in the page for it to be referenced to.
I think you might get some benefit from following this guide in our docs -> https://docs.newrelic.com/docs/agents/net-agent/additional-installation/new-relic-browser-net-agent
Can you review the above document and let me know how you get on if you need more assistance with it. I feel that passing this to your developers will help you to get your application instrumented for browser