Compressor 4.3.2

What OS is on your older mac? Have you already bought Compressor?

When you purchase, you get the current version.

But if you have already purchased, you can open the App Store in the older mac, and:

• select your account (bottom left), or click on Purchased (depending on the OS version in the old mac)
• find Compressor in the list, and click the download button

When you do this, you will be warned that the current version does not work, and asked if you want the most recent compatible version for your system. Confirm.

Go to the AppStore, the version there is all that's available.