What version of Numbers were you running?
You said in your initial post that "Numbers on my Macbook Pro indicates that I need to get the latest version of Numbers."
Will that version of Numbers open? Will it open files that have been stored only on your computer, and have not been sent to iCloud? The big push in recent Numbers updates/upgrades seems to have been to provide better inter device transfer of files. If you can get along without that, the version you have currently installed may continue to serve you.
If your machine is compatible with OS X (10.11) Yosemite, there may be a way to update to that OS. A definitive answer to that possibility would need to come from someone else, though. The procedures, if they exist, are beyond my ken.
Regards,
Barry