If you can’t save a password in Safari on Mac
You can use AutoFill to remember the passwords you enter for websites, then easily fill in the saved information when you revisit the same websites. If you can’t save your password for a website, you might have chosen to never save the password for that website. You can change this.
In the Safari app on your Mac, choose Safari > Preferences, click AutoFill, then make sure “User names and passwords” is selected.
Choose Safari > Preferences, then click Passwords.
In the list, select the website.
“never saved” should appear next to it.
If you chose to never save the password for this website (by clicking Never in the dialog that appeared when you first signed in to it), your password can’t be saved until you remove that status.
If the steps above don’t fix the problem, contact the website’s administrator and ask if the website allows passwords to be saved.