the are no clear instructions, and Its just not working.
every time the installer says that files are missing, but I downloaded them all. please help!

There is probably a file missing or it's wrongly named.

Go to your gog.com library, click the game box of Broken Age and download both files belonging to the installer into the same folder (see screenshot).

setup_broken_age_2.4.0.11.exe
setup_broken_age_2.4.0.11-1.bin

Make sure they're correctly named after the download is finished and then simply run the executable to start the installation. If the filename extensions ".exe" and ".bin" are missing, don't worry, they're hidden by default in Windows. Don't add them manually. The important thing is that the main part of the filenames look exactly like written above. E.g. under some circumstances some browsers add a number like "(1)" to the filename, which leads to your error message.