Whenever you build a link to an external site you must use the full address with HTTP:// or HTTPS:// otherwise the site treats it as an internal link and adds your domain to the front of it. This is the reason why your link is currently resulting in an error page or just reloads the page you are currently on.
To resolve this issue, you will need to add HTTP:// or HTTPS:// to your URL in the hyperlink manager, save the page changes, and then the link will work.
Important Note:
This fix is for the Editor. If you still have the Legacy Editor here is how you can move content.
Who can use this feature?
System Administrators | Owners | Publishers | Authors
Instructions
Navigate to the page with the broken link
Ensure that Live Edit is On
Click inside the Editor
Click on the link
Click the Edit Link tool
In the URL box, add HTTP:// or HTTPS:// to your link
Note: If the link currently is displaying either of those, we recommend double-checking that this link works in a new browser tab.
Click Update
To test the link, either use Preview Mode or click Open Link in the image toolbar.
Click the Green Checkmark to exit the Editor Widget
Click Save at the top of the page