Google Data Studio Connector and App Scripts
I found the issue, it was a simple case of forgetting to add the url to the whitelist.
I am working on a project for a client in which I need to load a lot of data into data studio. I am having trouble getting the deployment to work with my REST API. 
The API has been tested with code locally but I need to know how to make it compatible with the code base in App Scripts. Has anyone else had experience with working around this? The endpoint is a Python Flask application. 
Also, is there a limit on the amount of data that you can dump in a single response to the Data Studio? As a solution to my needs(needing to be able to load data for 300+ accounts) I have created a program that caches the data needed from each account and returns the whole payload at once. There are a lot of entries, so I was wondering if they had a limit to what can be uploaded at once. 
Thank you in advance