Hi there! Sorry to hear you're having trouble with the Hallow app not loading on your Mac. Let’s try to figure this out together.

First, can you tell me a bit more about what happens when you try to open Hallow? For example, does the app launch but stay on a loading screen, crash immediately, or does it just not open at all?

Meanwhile, here are some initial steps we can try on your macOS 10.15.7:

1. Check Internet Connection: Make sure your Mac is connected to the internet and that the connection is stable. Hallow needs internet access to load content properly.
2. Quit and Restart the App: Right-click the Hallow icon in the dock and select "Quit," or force quit the app from the Apple menu > Force Quit, then open it again.
3. Restart Your Mac: Sometimes a simple restart can help clear temporary glitches with apps.
4. Update the App: Check if there’s an update available for Hallow in the App Store and install it if so. Running outdated app versions can cause loading issues.
5. Log Out and Log Back In: If the app opens but gets stuck, try signing out of your account within Hallow, then sign back in.

If you’ve already tried those or if Hallow won’t open at all, the next step would be to clear any app cache or data, but that’s a little more involved on macOS and may require reinstalling the app:

- Reinstall Hallow:
- Open Finder, go to the Applications folder, and drag the Hallow app to the Trash.
- Empty Trash.
- Open the App Store, search for Hallow, and reinstall it.

Before reinstalling, you might want to back up any important data or check if your progress is saved in your account (usually syncing with server-side data protects your info).

Let me know what you’ve tried so far and what exactly happens when you open the app, so we can tailor the next steps!