documentclass{tikzposter}

begin{document}
        block{}{
            XXXXXXXXXXX
            begin{itemize}
                item XXXXXXXXXXX
                item XXXXXXXXXXX
            end{itemize}
            XXXXXXXXXXX
            begin{itemize}
                item XXXXXXXXXXX
                item XXXXXXXXXXX
            end{itemize}
            XXXXXXXXXXX
        }
end{document}