Provided that you already downloaded Pages from the Mac App Store in the past, here's how to do it:

Open the Mac App Store
Click on your account (at the bottom)
This will give you access to the "Purchased" pane.
Locate Pages and initiate the download from there.
You'll see a message telling you that the latest version is incompatible so it will download and install a previous yet compatible version.

If you've never downloaded the Mac version of Pages with your Apple ID, then you have two main options:

If your current Mac is compatible with macOS Big Sur, then you could install macOS Big Sur on an external SSD connected to your Mac (see this article from MacWorld)
If your current Mac is stuck at macOS Catalina, then you could create a secondary user account on a family member's or friend's Mac running at least macOS 11 Big Sur.

In both cases, you'll then need to open the Mac App Store, sign in with your Apple ID, search for Pages then click on the "Get" button.

Once the Mac version of Pages is associated with your Apple ID, you'll then be able to follow the first procedure explained earlier for your Mac running macOS Catalina.

Please note that the latest compatible version of Pages on macOS Catalina comes with a massive restriction: it's not possible to edit shared documents with the desktop app.

So, if you have shared Pages documents with other iCloud users, you'll be able to open those documents on your Mac but your changes won't get saved.

To collaborate with others on Pages documents, you'll need to do that from iCloud(dot)com.

This little restriction made me bite the bullet and upgrade my iMac to Big Sur.

And you, on which version of macOS is your main Mac running?

Want to receive this kind of FAQ automatically via e-mail alongside Apple news?
Just click on the thumbnail below to join the club