This page is safe to use. It’s a pretend sign-in form for trying SafeSite: nothing you type here is sent anywhere, and the button does nothing.
Start typing in the password box. Because this site isn’t on your list of safe sites, SafeSite should warn you, and its page icon should show ✗.
Afterwards you can choose Not now, or open SafeSite and turn checks off for this site. If you tap Trust this site, SafeSite won’t warn you on this site again until you mark it unsafe.