here are some suggestions, use at your own risk or contact support. the issue is can be caused by MS Edge, your device, firewall or antivirus. This is not a Turbotax bug. I use Edge and can reach the sign-in site

5am-5pm Pacific Time (8-8 Eastern) Monday - Friday
https://support.turbotax.intuit.com/contact
800-446-8848

1. Clear Browser Cache and Cookies

• Open Edge.
• Click the three dots (menu) in the top-right corner and select Settings.
• Go to Privacy, search, and services.
• Under Clear browsing data, click Choose what to clear.
• Check Cookies and other site data and Cached images and files.
• Click Clear now. Disclaimer: Your browser automatically saves temporary internet files to help pages load faster. Clearing this cache will sometimes fix website issues. Please back up all your personal files first, such as Favorites, to ensure you do not lose data.

2. Check Your Network and Firewall Settings

• Ensure that your firewall (including third-party firewalls) isn’t blocking the website.
• Power cycle your network hardware:
  1. Turn off your router and modem.
  2. Wait for 30 seconds.
  3. Turn them back on.
• Test the website on a different network (e.g., mobile hotspot) to rule out local network issues.

3. Flush the DNS Cache

• Press Win + R, type cmd, and press Enter.
• In the Command Prompt (run as administrator if you have that authority), type the following command and press Enter: ipconfig /flushdns

4. Try a Different Browser. To determine if the issue is browser-specific, attempt to access the site using a different browser (e.g., Chrome or Firefox).

The link you posted for the Intuit signin above is not the secure version of the TurboTax URL, but it's possible that the http link should normally redirect to the https (secure) version when it's working.  Maybe it's not redirecting properly.   In any case, try placing an "s", i.e., using https instead of http and see if that makes a difference when you go directly to the secure URL.   

NOTE:  You may wish to clear your browser Internet cache before trying again, or it may remember your previous results.

If using the direct https link didn't help, try using Private Browsing mode (aka Incognito Mode) to see if the error recurs.

If you still get an error message after all that, do you have a different browser to try?