Hi McGoily,
An 'Alias' is a pointer to an actual file. The most visible examples are the icons on the Dock, which, when clicked, launch the application to whom that icon belongs. You can't 'change' that icon from an alias to a Numbers file icon, but you can replace it with the actual file, IF you know where the file in located, and either move it to the local (ie, 'on your Mac') location currently holding the alias, or Save a copy in that location.
If your file has been saved to iCloud, or has been opened in Numbers for iOS, you may still be unable to open it with Numbers 3.6.2. Current iOS version is compatible only with current macOS versions of Numbers, which will not on OS X v 10.10.x (Yosemite).
You are unable to download updates to the current version of numbers because that version will not run in Yosemite—it requires macOS 10,13,x or macOS 10.14 (High Sierra or Mojave). Th App store carries ONLY the current versions of the iWork applications.
Regards,
Barry