Passing OAuth Credentials Between Calls for A Data Source

I am working with the Twitter Ads API and trying to pull data into Power BI. As best as I can tell from all of the documentation, the Ads API requires multiple calls to access (POST/GET to get the oauth token then POST/GET to get the data). I need to be able to set the response from a call as a variable in the next call in order to access the data. How do I do that? I feel ok about setting the initial credentials (client ID and access token) for the first call but I'm not sure how to do the additional calls.