You could put my code into the Backend and Public folder (in each file there’s a specific place for you to put in).
Then in your page code, import the get or post function to do it. You can look at this link Velo Web Modules: Calling Backend Code from the Frontend | Help Center | Wix.com to find out how to do that.
In regard to your code, it still misses the Token part in Authorization (based on the docs you gave). It should be
'Authorization': 'Token XXXXXXXXXXXXX'