The online management programs of TUM and LMU provide the possibility to export the class schedule as .ics file. Unfortunately importing those into Google calendar is very difficult.
I developed two tools to convert the calendar to be easily imported by Google. Please note, that all traffic runs via my server. You should not use these programs directly, but rather download the source code and run them yourself. If you nevertheless want to use them directly never use your LMU password somewhere else (e.g. e-mail).
TUM Calendar Converter
LMU Calendar Converter
Old Version: https://phynformatik.de/calendar-lmu-legacy/ (Describtion here)