lost computer

You cannot purchase a download of Elements 9.  You may be able to find a copy on eBay or similar seller.  However, that won't do you any good unless you have the catalog file.  So, you should search your external drive for a file named catalog.pse9db.   If you don't have that file, you are going to have to start a new catalog from scratch.  When importing your photo files to the new catalog, you may be given the opportunity to import any tags that are found in the metadata of the files.  They will be stored in a tag category called Imported Tags in the tag hierarchy.  You can then click and drag the individual tags to a new tag structure that you will have to build.

However, do not despair.  There are many features of Elements 2021 that will help you.  For example, face recognition will analyze your photos for people and you can then easily tag the people with their names.  Similarly, Elements 2021 will analyze your photos for their content and tag them with Smart Tags.  You can then search for any number of words that you might have used as keyword tags and the artificial intelligence of the program will do a pretty good job of returning results for you.

As hatstead says, if you did a backup of your catalog, you will be able to restore it using Elements 2021.  But it sounds like you only copied the photo files.  If that is the case, you will have to create a new catalog.  You will be able to restore all of the keyword tags if you saved all metadata to the files (using the Ctrl+W or menu commands).  If not, the keyword tags are automatically saved under other conditions, e.g. when you edit a file in the Editor.

Alternatively, did you save the catalog folder?  If so, it will be possible to restore it to your new computer.  But, depending on how the photos were originally stored, it may take some work to replicate the folder structure so that the Organizer's catalog database can recognize the files.

If you can confirm whether or not you saved anything other than the photos themselves, we may be able to give you further information.

And I too am sorry that you were affected by the fires.

Sorry about the loss that you and many others have sustained in this disaster.

If you have a backup of the Organizer, you should be able to restore it on a new computer:

https://helpx.adobe.com/photoshop-elements/kb/backup-restore-move-catalog-photoshop.html

As for Windows 10, I purchased a new destop with Windows 10 earllier this year, and it is a great operating system. Have not had any problems.