No debug log for WP multisite is created

Where is the debug.log file stored on multisites?

I have inserted into my wp-config:

define ('WP_DEBUG', true);
define ('WP_DEBUG_LOG', true);
define ('WP_DEBUG_DISPLAY', true);

and analogous to , a debug.log file should normally been saved in wp-content.

Neither in wp-content nor - as it is a multisite (in sub-directories) - in wp-content/uploads/sites, is somewhere a debug.log file.

Where is this stored normally in a multisite? Or better, as I cannot find any file, why it is not created?

I found this answer for example:

since track_errors is OFF at my shared hosting, too. But since I am not a coder: how exactly has this file to be and where and what to add in this file?

Thanks for your help in advance.

WP 5.1.1 • RAM 66.5 / 256M • SQL 231 • PHPv 7.2.13