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 > Preferences, 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 web page has fields AutoFill can complete.
Safari may be unable to tell which fields are for username and password, credit card number and expiry date, and so forth.
If your Mac or Apple keyboard has Touch ID and you want to use Touch ID to fill in usernames and passwords or credit card information, make sure you select Password AutoFill in the Touch ID pane of System Preferences. See Change Touch ID preferences.
If AutoFill still doesn’t work, the website may not allow it.
To turn AutoFill off, choose Safari > Preferences, click AutoFill, then deselect the information you want to enter manually.