Hi there! I understand you're having trouble opening Nextdoor on your Mac. Let's see if we can get this sorted out together. To start, could you tell me a bit more about what happens when you try to open Nextdoor? For instance, does the website not load at all, or do you get an error message? Are you trying to access it via a browser or the Nextdoor app on your Mac?

In the meantime, since you're using macOS 10.14.6 with Safari or possibly another browser, here's a simple set of steps we can try first:

1. Clear Your Browser Cache
Sometimes old data stored in your browser can cause loading issues. In Safari:
- Click on Safari in the menu bar > Preferences > Privacy
- Click 'Manage Website Data' and then 'Remove All'
- Close and reopen Safari, then try Nextdoor again.

2. Check for Browser Updates
Make sure your Safari or any other browser you are using (Chrome, Firefox) is up to date because Nextdoor works best on the latest supported versions.

3. Try Signing Out and Signing Back In
If you can reach the login page, try signing out of Nextdoor and logging back in. This can refresh your session and fix minor glitches.

4. Use a Different Browser or Incognito Mode
Sometimes browser extensions or settings interfere with websites. Try opening Nextdoor in a private/incognito window, or use a different browser like Chrome or Firefox if you have them installed.

If you've done any of these already or if the problem continues, please let me know what you tried and any messages you saw, so I can suggest the next steps.

Are you currently trying to use Nextdoor through the website or an app on your Mac?

Looking forward to your reply!