How to download a file from a sharepoint online document library using GRAPH API to local folder

I am trying to get a test file (ian wheeler ms.png) from a SharePoint online document library in the sub folder General to download to a local folder of C:Temp

using this question and answer microsoft-graph-download-file-via-rest-api

I am able to make a call in postman to return my file contents to postman. The call is

https://graph.microsoft.com/v1.0/sites/{{IT_Testing_Id}}/drive/root:/General/Ian Wheeler ms.png:/content

From the documentation here I see I have to make something of XMLHttpRequest call using the download URL which I have been able to retrieve using the List Drive Children call of

https://graph.microsoft.com/v1.0/drives/{{DriveID}}/items/{{ItemID}}/children

Is anyone able to explain how to make a XMLHttpRequest call using Graph API and POSTMAN please?

My end goal is to use these calls in an Web service call in BPA PLATFORM ref here so can the call be made in HTTPS?

Thanks in advance