Hello! I see you’re encountering an error message when trying to register on the Iubilaeum25 app on your Mac running OS X 10.15.7. Could you please tell me exactly what the error message says? Also, have you tried registering before, or is this your first attempt? Any details about the step you're stuck on or the data you've entered would help me guide you better.

Meanwhile, here’s a general approach to troubleshoot registration errors in the app:

1. Check Your Internet Connection
Ensure your Mac has a stable internet connection, as registration requires online access.

2. Verify Your Email Format
The app sometimes rejects emails it considers invalid—make sure your email address is correctly typed without extra spaces or characters.

3. Update the App
Although you’re on Mac, confirm that the app is the latest version available. Sometimes outdated versions have bugs affecting registration.

4. Clear App Cache or Data
If possible, try logging out and back in or uninstalling and reinstalling the app to reset any cached issues.

5. Try a Different Email
Occasionally, specific emails might be flagged. Test with another email if you have one.

6. Use a Supported Browser or Device If Applicable
Some web-based registration steps might require a certain browser. You can try registering via Safari or another browser on your Mac.

If these don’t resolve the problem, the official Jubilee FAQ suggests that errors during registration could be related to email validation or server issues on their side. Checking their FAQ or contacting their Info Point might be necessary if the problem persists—here is the official FAQ page: Iubilaeum25 FAQ.

Let me know more details about the error message, and I can help you further! Are you satisfied with this initial guidance?