First time API connection - Base64 Encoded

V,

I am sorry but I have read the post and still can not figure this out.  I am a CPA that took a few C++ courses in college 20 years ago, and spent alot of time developing UI solutions using MS Access and SharePoint as a datawarehouse during that time.  I like to think I was doing powerplatform stuff before the powerplatform was branded.

Can you look at the advanced editor screen and point me in the right direction of where I need to code?

I did confirm this is a GET, not POST

I have verified the API_KEY and TOKEN are correct.  When encode to Base64 I use the values in the converter like this API_KEYTOKEN.  Here is how the content provider describes the headers:

Authentication in header can use Authorization field in following format:
Authorization: Basic {basicHash}
basicHash is base64 encoding of resulting string from: {API_KEY}:{TOKEN}
Example authorization header: $header = ['Authorization : Basic ' . base64_encode(API_KEY . ':' . TOKEN) ];

Should I be encoding the API_KEY and TOKEN differently?

I get invaild credentials when I use API_KEYTOKEN in the base64 converter.  But if I add the :, like API_KEY:TOKEN in the converter I get a Bad Request error, so it never passes to the credentials.

I would also take a reccomendation on a developer that can assist.  I am a one man shop at the moment but can pay for some help to get this connected.