Complete these steps once — takes about 2 minutes.
Go to developer.spotify.com/dashboard and log in with your Spotify account. Then tap Create app in the top-right corner.
Enter any App name and Description (e.g., "True Shuffle" and "A real shuffle of all my music").
In the Redirect URIs field, enter the URL shown below exactly, then tap Add:
Tap to select · copy it into the Redirect URIs field
Under Which API/SDKs are you planning to use?, check Web API. Accept the terms and tap Save.
After saving, you'll be taken to your app's Basic Information page. Your Client ID is the 32-character code shown at the top. Tap the copy icon next to it.
Go back to True Shuffle, paste your Client ID into the field, and tap Save & Continue. You'll only need to do this once.