If AutoFill doesn’t work in Safari on Mac
If you can’t fill in information you previously entered on websites, try these suggestions.
In the Safari app
on your Mac, choose Safari > Settings, click AutoFill, then make sure “Usernames and passwords” is selected.Make sure any information you want to autofill is saved in your My Card in Contacts. Safari can fill in only contact information that’s in Contacts. For example, if a form requires your phone number but it isn’t on your contact card, you must fill it in manually.
Make sure the webpage has fields AutoFill can complete.
Safari may be unable to tell which fields are for user name and password, credit card number and expiration date, and so forth.
If your Mac or Apple keyboard has Touch ID, and you want to use it to fill in usernames and passwords or credit card information, choose Apple menu
in the sidebar, then turn on “Use Touch ID for autofilling passwords” on the right. (You may need to scroll down.) See Touch ID & Password settings.
If AutoFill still doesn’t work, the website may not allow it.
To turn AutoFill off, choose Safari > Settings, click AutoFill, then unselect the information you want to enter manually.