From eOne I see that SmartConnect 2014 R2 Released. This release let’s SC work with GP 2015 among other things. Kudos to the eOne team for a nice job.
The eOne Dynamics GP and CRM Blog: SmartConnect 2014 R2 Released
Microsoft & the GP EcosystemDevelopment & IntegrationGP 2015
Archived post from 2015. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.