Hi there! I understand your EE app is not opening on your Mac running OS X 10.15.7. Let’s try to get this sorted out together.

First, just to clarify:
- Is the app installed from the Mac App Store or are you accessing EE services via a browser?
- When you try to open the app, do you see any error messages or does it just not respond?
- Have you tried restarting your Mac recently?

In the meantime, here are some straightforward steps you can try:

1. Restart Your Mac: This can clear temporary glitches that might be preventing the app from opening.

2. Delete and Reinstall the App:
- Go to your Applications folder.
- Find the EE app, drag it to the Trash, and empty the Trash.
- Restart your Mac.
- Download the latest version of the EE app from the Mac App Store and install it.

3. Check for Software Updates:
- Go to the Apple menu > System Preferences > Software Update.
- Ensure your OS X 10.15.7 is fully up to date.
- Sometimes apps need the latest OS patches to run correctly.

4. Account Refresh:
- Occasionally, the issue relates to your EE account syncing.
- If possible, contact EE customer support to perform an account refresh.
- After that, try reinstalling and logging back into the app.

5. Internet Connection:
- Verify your internet connection is active and stable.
- Sometimes, a weak or no connection might prevent the app from launching properly.

If these haven't helped, let me know if you noticed any error messages or specific behaviors. That’ll help me guide you with more precise steps.

Are you okay trying these? Let me know how it goes!