If you don't have a card for this website in the SafeInCloud database, then you can add it right now by filling the Login and Password fields. Then pressing the Add button. The extension will add this card to the database and autofill the login form on this webpage.
If you already have a card for this website in the SafeInCloud database, make sure that this card has enabled the Use for Autofill checkbox. This card must also have non-empty Login and Password fields, and a Website field that matches the address in the browser. The exact match is not required. They only have to have the same domain, e.g. online.citi.com matches www.citi.com.
If the error still remains, press the Edit button at the bottom of the card. In the card editing window press the Autofill icon on the toolbar.
In the appeared Autofill dialog check that all the fields have correct autofill attributes (like on the screenshot below).