Adobe InDesign is the second software requirement to use SignAgent Pro™.
Versions of Adobe InDesign CC will work, up to and including CC 2018. For more info on which versions are compatible, check out this article here: Adobe InDesign Compatibility
You can learn more here: Adobe InDesign
If you need a trial version to get started, you can find that here: InDesign Trial
Note that InDesign 2019 is not currently compatible, as we're waiting on an update that will allow InDesign 2019 to connect to our authentication server.
InDesign 2018 is available for an easy and free downgrade for anyone who has an active Creative Cloud subscription. You can see details on that here: Install Previous Version of CC Application