WordPress Multisite on addon doamin on windows server

Hi,

im trying to set up wordpress multisite on a addon domain which runs under windows server (godaddy)
my main installation on [main domain/addon domain]
ex: https://www.xxxx.com/multisite-installation
[multisite-installation] directory pointed to another domain called yyyy.com.
yyyy.com is the addon domain.
i want to set up wp on addon domain.

i followed instructions and did exactly what need to do.

after editing wp-config.php and web.config site gives a 500 internal server error.

can anyone help me?
thank you