The sender and receiver should use the same CRC algorithm. The sender calculates the CRC value of the sent data and appends the CRC value. The receiver calculates the CRC of the received data and compares it with the following CRC value. The CRC calculation from the data is the same in both cases.
As an aside, I think CRC8 and CRC_8() in your sample code are poorly chosen names since they are similar enough to cause confusion.