Can you try finding other log files ? webserver log, syslog (not sure there's something like that on Windows) ? We can't really help if we don't find an error message.
Can you share the system config ? operating system, webserver (probably apache), php version, php extensions, database server (probably mysql) ? And their versions. From your last screenshot I guess you're using xampp. Are you running the latest version ?
If no error message can be found we need to know how we can reproduce that issue
php flarum info command in the Flarum directory should give some of those details, but I don't know if it will work with an incomplete install...