\node[blueb, label=center:{\sffamily\bfseries\color{white}a}] (RCP) {};
\node[blueb, right=of RCP, label=center:{\sffamily\bfseries\color{white}b}] (Aut) {};
\node[blueb, right=of Aut, label=center:{\sffamily\bfseries\color{white}c}] (Bro) {};
\node[blueb, right=of Bro, label=center:{\sffamily\bfseries\color{white}d}] (Pub) {};
\node[
blueb,
inner sep=0pt,
shift=($(RCP.south)-(RCP.north)$),
yshift=-\pgfkeysvalueof{/tikz/node distance value},
fit={(RCP) (Pub)},
label=center:{\sffamily\bfseries\color{white}asd}] (Dm) {};