I found a soloution.
The problem was, when I downloaded the launcher with Microsoft edge i didnt click on save but on execute. After that the TechnicLauncher.exe was nowhere to find. After downloading it again and saving it in my downloads folder I could use the exe there to start the program.
I have the same Problem. After installing the launcher there is no button to start it and i cant find the program. Neither in %appdata% nor somewhere else.
Funny thing is, the launcher started after Installation and worked. But after I closed it i couldnt find how to start it again.