FileMaker Pro is the first software requirement for using SignAgent Pro™. The most recent version that is compatible is FileMaker Pro Advanced 17
Development is no longer ongoing for SignAgent Pro, so future versions of FileMaker Pro may or may not work.
For more information on which versions are compatible, check out this tutorial here: FileMaker Pro Compatibility
You can learn more here: FileMaker Pro Advanced
If you need a trial version to get started, you can find that here: FileMaker Pro 17 Trial