Its not connected to the payment system, but there's no reason you couldn't do it manually. Just have a page that only you could access, then once you've confirmed payment you could type their email in.
Not perfect but could work if you're not getting 1000's of users. If you are getting 1000's of users paying, sponsor the development and we'll get it connected in so it does what you need it to do.
Check the servers error logs for hints on that one. If php is complaining about something it should turn up in the
ACP -> DASHBOARD -> ACTIVITY LOGS -> ERROR LOG
but if php thinks its been sent then something at server level is blocking it then there may be no php level error.
That log looks like the apache activity log, its not showing any errors. See if there's one called error_log as that might be more useful for spotting the cause of issues.
This is a screenshot of audiopro. What about it is the wide look?
The other screenshot is of a fresh install where there isnt much content. Once you start getting content in the system it will automatically come out on the top page.