SDA & SCL come from A4 & A5 on '328P based boards. They are duplicated as SCL & SDA on the Uno for example.Do you have 4.7K resistor from SCL to 5V, and from SDA to 5V? Those are needed for I2C. I don't know if they are included on the Grove-RTC.
4K7 Pull-up resistors are included on the Grove module, so that's not the problem. Schematic.You should connect A4 to SDA, A5 to SCL, 5V and ground to the Nano. Then try running the i2c scanner sketch and watch the serial monitor.
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