Clicking the sign in link results in "Unknown client or client not enabled"

[aaronsgithub]

I downloaded the repo and installed the dependencies with make install.

I noticed in the app.py file, the CLIENT_ID and CLIENT_SECRET are read in as environment variables.
I've generated them using the instructions provided in the quickstart tutorial here and set these as environment variables.

I also set the environment variable REDIRCT_URI to "https://console.truelayer.com/redirect-page"

But when I run the development server using make run, a new tap opens at the domain https://login.truelayer-sandbox.com/error? with an error ID and request ID in the url string, and a message of "Unknown client or client not enabled".

Have you any advice on how to proceed to get the demo code in this repo to work?