The current retail version is 8.978
it is likely that your install path is incorrect with the installer and not updating.
You can find the install path by loading your Battle net launcher and click on cog icon for game settings
this is the standard install path
Mac Retail. /Applications/World of Wacraft/_retail_/
Mac TBC Classic. /Applications/World of Wacraft/_classic_/
Mac Classic. /Applications/World of Wacraft/_classicEra_/
fix the install and reinstall