Files.c64audio.com has been decommissioned.
The old server you were trying to access has been decommissioned. Emails were sent with alternative SendOwl links to all the content you had purchased or owned.
Do not try to log into this new website with your old credentials: they're not valid. However, you can create a new account here with the same email address.
However, please email email@example.com if you did not receive any SendOwl Links and you would like to recover your files. We did keep the database intact.
Note that it's always good practice to download online content to your own backup area because online storage is only ever one unpaid bill away from being nuked.
Thanks for your support over the years. The best is yet to come.