Yeah, for some reason this doesn’t work with v1.6.3. I downgraded to 1.5.3 and it worked just fine.
Downgrading from v1.6.3 to v1.5.3 fixed this ^.
I’m having the same issue:
There is no “Enable Salesforce integration” option available on the forms with the latest version of Gravity Forms.
Screenshot -> http://d.pr/QAzf