This Connect option is not clear. There seems to be no help page for this, and the page https://help.researchgate.net/hc/en-us/articles/14292811772689-Logging-in does not mention Google. In https://www.researchgate.net/settings/connect the explanation is: "Connect your ResearchGate account with other services to find researchers and share updates." When I click on "Continue with Google", I come to a Google login page, that reads "Sign in with Google" and "Sign in to continue to ResearchGate". It seems to me that there is not connection between ResearchGate and Google Scholar, just with one's general Google account. Perhaps, the only result may be that Google will track your activities in ResearchGate.

You can link ResearchGate and Google Scholar by adding the URL of your Google Scholar profile to the "About" section of your ResearchGate profile and vice versa, and by manually adding or importing publications between the platforms. Since there is no direct automatic connection, you must manually update your profiles to keep them synchronized.