The condition of the packaging does not matter as far as installation goes. Files can be downloaded rather than installed using a disc. If the license was used previously and has not been formally transferred to your ownership then that should be done. Transfer an Adobe product license
If the package is unopened then you are not likely using the correct number for the serial number because the number will not be visible from the outside of the package.
If you are using the correct serial number then you will probably need to contact Adobe Support directly to get help with it. They are not usually available on weekends.
For the link below click the Still Need Help? option in the blue area at the bottom and choose the chat or phone option...
Make sure you are logged in to the Adobe site, have cookies enabled, clear your cookie cache. If it fails to connect try using a different browser.
Serial number and activation chat support (non-CC)
https://helpx.adobe.com/contact.html?step=PHSP-PHXS_downloading-installing-setting-up_licensing-activation_stillNeedHelp