So, I downloaded Xcode 7 and installed it to be able to use free provisioning to test my app on an iPhone running iOS 8.3 before subscribing to the developer program. Connecting my iPhone, I see it in the toolbar and on the device list in Devices window.
I also added my Apple ID in the Preferences' Accounts Tab and it shows "Free" under iOS and Mac next to my name. Nevertheless when hitting the play/build-and-run button Xcode at first starts building the app but before transferring, I guess, it stops and tells me it was "Unable to find a team with the given Team ID '<My ID>' to which you belong. Please contact Apple Developer Program Support. https://developer.apple.com/support", any suggestions what to do?
I removed and added my account several times, getting the same message all of the times.