Forms for Confluence is compatible with Confluence 6.5.0 - 7.0.1
Previous versions are available under Forms for Confluence and Form Mail NG
You can always check the compatibility for other versions of Confluence from the Atlassian Marketplace
Installation & Licensing
Forms for Confluence is available from the Atlassian Marketplace and can be downloaded directly from the Universal Plugin Manager or from the Atlassian Marketplace.