Can I download Keynote for iMac

If your iMac is a 2017 model, then it does not support macOS Sonoma (14.*)¹ which is required for the current Keynote (v14.4) in the Mac App Store.

If you never installed Keynote from the Mac App Store since Oct 2013, or if your iMac came with Keynote pre-installed, then you cannot install any older version of Keynote compatible with the current operating system on that iMac.

If you did previously install Keynote, you can get a compatible version of Keynote for the older version of macOS you currently have installed on your iMac:

1. Launch the Mac App Store and sign-in with the same Apple ID that you used to previously install Keynote.
2. Press ⌘+0 (zero) to open the previous purchases panel
   1. If Keynote is found there with a download icon, click that.
   2. One or more dialogs will appear. Do not click Cancel.
      1. When asked if you want to install the last compatible version of Keynote for this operating system. Click OK.
3. Keynote will be installed into your Applications folder in the Finder sidebar.

¹ Versions of Pages, Numbers, or Keynote released after v14.4 may require newer operating system criterion.

sure ‎Keynote App - App Store