How do I install the addon?

Go to the Releases tab, which can be found here

Download s4animtools.zip from the latest release.

Open Blender, click Edit, then Preferences.

Click Preferences, then go to Add-ons. Click on the small arrow on the upper-right and click "Install from Disk..."

Select the zip you just downloaded and click Install Add-on

With Blender 4.5, your preferences are automatically saved, so now you're ready to start making poses or animations!