A similar topic. See how the receiving block is built there, and read @ABG's advice on DelimiterByte (10).
You have "serial.println ()" in your arduino code, it's ok. In clock blocks, use a "ReceiveText" block with negative bytes, such as -1, instead of a "connect" block.
In the designer, in the properties of the Bluetooth component, set the value of "Delimiter Byte" to 10.