Email sent to me for my purchase of Maximum Security 10 downloads the Windows version and I have a Mac!!!

@pragmatic Thank you for answering this question!

@jskinner29  We checked our trouble ticket system and it seems that our support center is already handling your issue. You can go to the URL provided by @pragmatic and download the Mac version to install.

Maximum Security allows you to install on Windows, Mac, Android, and iOS devices. Once your Mac is installed and registered, here's an online doc that walks you through how to enable protection on different device types from the Maximum Security console:
Protecting other devices using an active subscription

Alternatively, after you've installed your Mac, you can go to Trend Micro Account Portal, and download and install to other devices.

Thanks and please let us know if you have further questions.