I don’t remember the email address that was used to establish my account.

See if this helps:

https://helpx.adobe.com/account/individual/manage-your-account/cant-find-adobe-account.html

If the software version is pre-CS5 or CS6, you won’t be able to activate it. The aged-out activation servers for legacy CS2, CS3, & CS4 were removed from service some time ago.  And, depending on which operating system you have, you may not be able to use legacy products on a newer device.

MODERN OPTIONS:

• Photoshop Express (free)
  https://www.adobe.com/products/photoshop-express.html
• Photoshop Elements (3 year license)
  https://www.adobe.com/products/photoshop-elements.html
• Photography Plan (Photoshop & Lightroom bundle)
  https://www.adobe.com/creativecloud/photography/compare-plans.html

Hope that helps. 

If you don't remember which email address is linked to your Adobe account, try signing in with any email addresses you commonly use. If none of them work, check your old inboxes for Adobe purchase receipts or subscription emails they'll usually show which account was used. If you still can't identify it, Adobe Support can help locate the account after verifying your purchase details or billing information.

 Thanks for posting to this public discussion forum, ​@LAURA HOCHFELD.

I appreciate your long-term use of our software and I apologize for any problems you have encountered accessing your previous purchase.

What version of Photoshop are you trying to download and install? I see that you did contact us directly and mentioned a serial number, but there are not many other details available.

Please see 

 for information on how to download and install older versions of Photoshop and Photoshop Elements. You will need to be logged in under the correct account to access the files, and I don’t see any software titles registered under the account you used to start this public discussion thread.

Please see https://helpx.adobe.com/account/individual/sign-in-and-security/security-and-recovery/reset-adobe-password.html for details on how to request a password reset if you do recall the email address that was used to register the software.

use https://helpx.adobe.com/manage-account/kb/unknown-charge-on-bill.html?linkId=100000379229962 to find your account.

This is a public forum, not Adobe support... other users can't help
This is the new CORRECT way to contact support
https://helpx.adobe.com/contact.html?rghtup=autoOpen

- and enter AGENT in the box asking How can we help you?