The clone feature of the radio is used to send the current memory contents to CHIRP and to receive updates from CHIRP. The timing and sequencing can be a little tricky the first few times you fumble through the process. And after a few cycles it becomes second nature.
The following instructions are directly from the FT8800 manual with pictures added, and instructions on what to do with CHIRP.
Connect to the radio
Connect the cloning cable to the computer and radio and wait for the operating system to download and install the driver. Or if the version of O/S used does not support this capability. Manually install the driver for your specific USB to radio cable.
Entering Clone Mode
Power on the radio while holding the LEFT V/M key.
Rotate the right top knob until “Clone Start” is displayed.
Press the SET key, the screen will go blank and return to “CLONE”
At this point you are setup to either upload a memory config to the radio or download a memory config from the radio. If this is the first time you are connecting to CHIRP you will want to first download the radio into CHIRP so you have something to edit.