aobs-tikz package is not well installed. After installation through MPM, README and aobs-tikz.pdf are extracted to corresponding doc folder, but .ins and .dtx are not processed so nothing else is installed.
In particular tikzlibraryoverlay-beamer-styles.code.tex
is missing.
This will be fixed with the next update.
The problem is fixed, but now the package contains the (probably) unwanted file