MPLAB® Harmony v3 Peripheral Libraries on SAM D5x/E5x: Step 4
Generate Code
When done, before generating the code, click the Save icon as shown.
Save the configuration in its default location when prompted.
Generate the code as shown.
Click on the Generate button in the Generate Project window, keeping the default settings as shown in the accompanying image. If prompted to save the modified configuration, click Save.
As the code is generated, MPLAB® Harmony Configurator (MHC) displays the progress as shown.
Examine the generated code as shown.
The MHC will include all the MPLAB Harmony library files and generate the code based on the MHC selections. The generated code would add files and folders to your Harmony project as shown. Among the generated code, notice the peripheral library files generated for RTC, SERCOM 3 (as I²C), SERCOM 2 (as USART), DMA, and PORT peripherals. The MHC also generates a template main file (main_e54.c).
Build the code by clicking on the Clean and Build icon 
and verify that the project builds successfully.
At this point, you are ready to start implementing your application code.