I need to recover the VC because of the DFW issue. But display the below.
The NSX manager version is: 6.3.5
Yep, I'd agree with lmoglie - a 403 forbidden response with "Auth header not present" indicates that the API call was run without specifying the NSX manager username and password.
It looks like you are just visiting that URL in your browser. You should use a proper REST client for this purpose to provide the required authentication header etc. Have a look at postman or the Firefox REST client. For Linux, you can use 'curl' as well.
You can find out more about the NSX REST API in the APU guide (page 26):