DRA821U: Questions about the DCC Application Report "Continuous Monitor of the PLL Frequency With the DCC"

Hi  experts

For the Application Report https://www.ti.com/lit/an/spna211/spna211.pdf

Q1:Does the application note apply to DRA821 platform?

Q2: Why the  asynchronous error shall be calculated as below? Would you give me more explanation. 

Q3: Why the multiplication factor is 2？

Look forward to your answers. Thank you . 

Fang He