Hi, Suraj,
For the LPC4322 and LPC54628 connection, you have attached the LPC546xx-540xx_Dev_brd_schematics_Rev-F_180708.pdf, pls refer to the sheet 11,12 and 13, the three sheets gives the connection.
In short the LPC4322 converts USB commands to SWD signal timing for LPC54628 so that you can debug the LPC54628. BTW, the uart0 of LPC4322 is connected to uart0 of LPC54628, so the USB of LPC4322 is a composite USB protocol which has CDC.
Pls download UM11035.pdf from the link:
https://www.nxp.com/webapp/Download?colCode=UM11035&location=null
Hope it can help you
BR
XiangJun Rong