FlatRedBall.Spine provides the ability to load Spine files in code or in your FlatRedBall project through codegen.
FlatRedBall.Spine is currently under construction. Lots of things may change so use at your own risk for the time being
You must own a license to Spine to use this in your project. For more information see the Spine runtimes license here: https://github.com/EsotericSoftware/spine-runtimes/blob/4.1/spine-monogame/README.md
TLDR:
You are the user, so you must own a Spine license:
You can integrate the Spine Runtimes into your software free of charge, but users of your software must have their own Spine license.