SAVE BUTTON not working on Annual Recurring Billing for MS365 Personal, it's stuck on a loop at Step 3 of 4

Try the following steps in order, focusing on the billing details and browser environment, since similar issues have been resolved that way:

1. Verify address and payment details exactly match card records
   A similar Microsoft 365 purchase flow issue was resolved when the billing address on the subscription page matched exactly the address on file with the bank (including abbreviations, punctuation, and postcode).
   • Open the subscription/payment page again.
   • Carefully re‑enter: name, street, city, state/region, postal/ZIP code, and phone number exactly as your bank has them.
   • Re‑enter the card details and try Save again.
2. Temporarily disable security software and retry
   In the same resolved case, temporarily deactivating third‑party security software (such as Trend Micro) helped the page complete the step.
   • Temporarily pause any antivirus, web shield, or security suite on the Mac.
   • Close the browser completely, reopen it, sign back in to the Microsoft account, and retry the recurring billing setup.
   • Turn security software back on immediately after the attempt.
3. Try a different browser or private window
   • Open a different browser (for example, if using Safari, try Chrome or Edge).
   • Or open a private/incognito window and sign in again to the Microsoft account and subscription page.
   • Repeat the billing step and click Save.
4. Check for profile or country/currency mismatches
   Country or profile mismatches can block subscription conversions.
   • Go to the Microsoft account profile page and confirm the country/region matches the card’s country and the region used when Microsoft 365 was activated.
   • If they differ, update the profile to match and retry the billing step.
5. Try a different payment method
   Another user with a payment‑flow error fixed it by changing the payment method.
   • Add a different card or payment option on the Microsoft account billing page.
   • Select that method during the recurring billing setup and try Save again.
6. If still stuck, contact Microsoft Support
   If the subscription is active but the flow will not complete, contact Microsoft Support so they can check the account and complete or adjust the recurring billing on the backend.

References:

• microsoft 365 install issue - Microsoft Q&A
• Trying to use an Office365 product key and "getting error PaymentAuthenticationVerificationFailed" - Microsoft Q&A
• Problems renewing a Microsoft 365 subscription
• Troubleshoot payment option issues
• You can't complete a purchase in the Office 365 portal
• Pay for a past-due Microsoft subscription