Accessing get_metadata endpoint without Dropbox Javascript package

For fun, I'm making a cataloging web app using asp.net core 2.1 MVC and javascript.  I don't need a frontend framework, so I don't want to bring in the whole NodeJS npm situation into this project.  I'm trying to access https://api.dropboxapi.com/2/files/get_metadata using fetchAPI and Chrome and I am getting this error: 'Access-Control-Allow-Origin' header in the response must not be the wildcard '*' when the request's credentials mode is 'include'.

Their is a similar question on this forum, and the answer was to use the Dropbox Javascript library.  I thought this API was like any other restful api where all you needed was to send http requests to endpoints.  Is the library required?

Here's all my javascript code.  I am using the chooser to get the id of a folder, then I need to make a call to get_metadata to get the path (why doesn't chooser return the path itself? I guess the folder names are too secret.)

var options = {

    // Required. Called when a user selects an item in the Chooser.
    success: function (files) {
        //alert("Here's the file link: " + files[0].link);
        console.log('files[0]:', files[0]);
        dbxGetPathFromId(files[0]);
    },

    // Optional. Called when the user closes the dialog without selecting a file
    // and does not include any parameters.
    cancel: function () {
        console.log('Canceled');
    },

    // Optional. "preview" (default) is a preview link to the document for sharing,
    // "direct" is an expiring link to download the contents of the file. For more
    // information about link types, see Link types below.
    //linkType: "preview", // or "direct"

    // Optional. A value of false (default) limits selection to a single file, while
    // true enables multiple file selection.
    multiselect: false, // or true

    // Optional. This is a list of file extensions. If specified, the user will
    // only be able to select files with these extensions. You may also specify
    // file types, such as "video" or "images" in the list. For more information,
    // see File types below. By default, all extensions are allowed.
    extensions: ['.NoEmptyFiles'],

    // Optional. A value of false (default) limits selection to files,
    // while true allows the user to select both folders and files.
    // You cannot specify `linkType: "direct"` when using `folderselect: true`.
    folderselect: true, // or true

    // Optional. A limit on the size of each file that may be selected, in bytes.
    // If specified, the user will only be able to select files with size
    // less than or equal to this limit.
    // For the purposes of this option, folders have size zero.
    sizeLimit: 1, // or any positive number
};

var button = Dropbox.createChooseButton(options);
document.getElementById("dropbox-btn").appendChild(button);

function status(response) {
    if (response.status >= 200 && response.status < 300) {
        return Promise.resolve(response);
    } else {
        return Promise.reject(new Error(response.statusText));
    }
}

function json(response) {
    return response.json();
}

function dbxGetPathFromId(file) {
    // do an ajax call to dbx api, print the result
    // post to https://api.dropboxapi.com/2/files/get_metadata with auth
    // use json 
    reqData = {
        "path": file.id
    };
    apiURL = 'https://api.dropboxapi.com/2/files/get_metadata';

    fetch(apiURL, {
        method: 'post',
        headers: {
            "Content-type": "application/json; charset=UTF-8"
        },
        body: reqData,
        credentials: 'include'
    })
        .then(json)
        .then(function (data) {
            console.log('Request succeeded with JSON response', data);
        })
        .catch(function (error) {
            console.log('Request failed', error);
        });
}