Updated information regarding registration in Austria can be found on the website of Federal Ministry Republic of Austria Interior :Erfassung und Aufenthalt (bmi.gv.at)
General information about registration in English: https://www.bmi.gv.at/Ukraine/files/Information_fuer_Ukraine_Vertriebene_DinA1_20220317_v7_EN.pdf
General information about registration in Ukrainian: https://www.bmi.gv.at/Ukraine/files/Information_fuer_Ukraine_Vertriebene_DinA1_20220317_v7_UN_aktuell.pdf
Information about registration in Carinthia: https://ukraine-info.ktn.gv.at/EN/registrierung-vertriebene
Information about registration in Styria: https://www.ukrainehilfe.steiermark.at/