If the build scan plugin is applied, the build data is always captured on the machine where the build is run, but not necessarily published to scans.gradle.com depending on the publishing settings. For example, if you have the plugin applied and then run a build with --no-scan, nothing will be sent to scans.gradle.com and no link is shown on the console, neither.
Re: the TOS agreement, this is something we intend to improve in that you can agree/disagree externally, i.e. from the cmd line when running a build, or via system properties. Currently, you could do something like this:
termsOfServiceAgree = System.getenv("CI") || tosAccepted
and add tosAccepted = true to the gradle.properties file in your Gradle home directory.