Hi Welton,
First I want to know the version of your Starter, IR version or Bluetooth version?
Please send me a photo of the bar coded sticker to check.
If IR version then it doesn’t included a Bluetooth module so can’t be connected to makeblock app by Bluetooth.
If Bluetooth version, please make sure the Bluetooth module is connected to port 5.
Here you can download user manual for Starter, please check.
http://learn.makeblock.com/en/starter-robot-kit/
Yes you can only contact it by USB cable, if you want Bluetooth connection, you need a makeblock bluetooth dongle.
Thanks.