Cool feature but it can eat a lot of space. We would need to click on activate debug and the file would then be created and start capturing php errors the same way LSCP does when you enable debug. Once you have finished debugging you disable this option.
I took a screenshot of how LSCP does it. Maybe it can give some idea.
Outputs to WordPress debug log. To prevent filling up the disk, this setting should be OFF when everything is working. The Admin IP option will only output log messages on requests from admin IPs. The logs will be output to wp-content/debug.log.