Hi @ qimin liu,
Unfortunately the link from where to get the activation code for APU compiler is shown in a previous step of the installation. It is easy to miss it, we did that a lot of times at the beginning.

To get the activation code follow these steps:
1. Go to https://www.nxp.com/webapp/swlicensing/sso/downloadSoftware.sp?catid=NXP-APU-COMPILER
2. Read the Software Terms and Conditions and click the I Agree button if you are OK with them.

3. Click on the License Keys tab.

3. Here you will find the Activation Code

Hope this helps,
Paul