so to download amazon prime it says need 11.4

wildcardjack wrote:

I have HIGH SIERRA macOS Catalina 10.15.7 but to get amazon prime it says to download macOS 11.4

High Sierra is 10.13.x

If you want to upgrade to 11.4 (or later):

The model year of a MacBook Pro is available at Apple menu > About This Mac.

A late 2013 and mid 2014 can be upgraded to the latest  version of Big Sur macOS 11 but no later. See: How to get old versions of macOS - Apple Support

An early 2015 or later can be upgraded to the current version of Monterey macOS 12. See: How to upgrade to macOS Monterey - Apple Support

If you can't or don't want to upgrade to 11.4, you should be able to watch Amazon Prime video in an internet browser. If Safari doesn't work, the current version of Chrome will.

... to download amazon prime WHAT ? you want the converted iPhone App? for WHAT?

Use a Web Browser like everybody else using a computer. Forgetabout that app, it is NOT NEEDED.