Software not accepted after clean-install

if possible, you should have applied all available Mac software updates.

MacOS older than 10.9 Mavericks (fully updated to include Safari 9) can not make hardly any secure connections or validate certificates.

if possible, update to at least MacOS 10.11 El Capitan, and apply all updates to that version.

Any DVD, or just specific DVDs with codes?

Given the age, other issues may well exist too, and which may have then triggered the suggestion for that re-install.

it’s also possible the certificates involved have simply expired, too. Maybe setting the lock back a decade or more might help.

And I’d hope you have backups somewhere.

Hi,

You can try downloading a compatible previous version through your purchase history on the Mac App Store, though Apple no longer allows direct redownload of older versions for many modern macOS releases.

Official App Store Method

• Open the App Store on your Mac.
• Click on your account name or profile icon in the lower-left corner.
• Sign in with the Apple ID originally used to purchase Final Cut Pro.
• Find Final Cut Pro in your Purchased list.
• If you have a newer version installed, move it to the Trash first (or compress it as a backup).
• Click the download/cloud icon; if available for your OS, it may prompt you to download a compatible older version. 

Thank you, Mr Hoffman! The problem is with DVD's with key codes. The Genius suggested the clean install because my Mac had been boxed up for four years and I had forgotten my password! I had written the PW in the "set-up pamphlet" in case I forgot, but upon delivery of my household items by movers the pamphlet was missing.

I will try "The Hoffman Clock Maneuver!"

P.S. Yes, I have back ups, but I have yet to try them on a new version of Final Cut.

Thank you, kaz-k! My Final Cut Studio 2 came in disc format, but considering the cost ($1,200 back then) and my history as an Apple/Mac buyer (since 1990) I would think they would have a record of everything I have ever purchased from them.

Hello, Grant,

I gave it a shot, but my browser (Safari) is no longer acceptable by the Apple servers - it will not get a secure link so it is a no-go. Perhaps an Apple Store can load it for me. I will check. Thank you for your assistance all the same.

Safari older than Safari 9 cannot connect to the Mac App store.

The way you get older versions is detailed in this article:

How to download and install macOS - Apple Support

If you have ANY version of macOS installed, DO NOT attempt to remove it and drop back to the built-in tools, because most Macs before 2010 have no built-in tools.

if you really have a stock standard 2007 MacPro 42 lb tower model, you may be stuck at 10.7.5

only 2008 and later models can run up to 10.11 El Capitan.

Alas, the Clock maneuver did not do the trick, but I thank you anyway for your assistance.

Thank you, Grant! I was running 10.6.8. for years without issue, but did not need to re-install Final Cut Studio 2. I will try this.