Because the Douyin applet is not authorized.

Authorization method: 1. First, we open the phone and enter the desktop, then find the Douyin icon and click to open it. After entering the Douyin video interface, we click on My Options in the lower right corner of the interface. 2. Next we will enter the My interface of Douyin. We click on the three horizontal lines icon in the upper right corner of the interface. 3. Then a sidebar will pop up on the right side of our Douyin software. We click on the mini program option in the sidebar. 4. After entering the mini program interface, we can find our mini program at the bottom of the interface. 5. After we click to enter the program interface, a Douyin authorization prompt will pop up. We can click the allow option in the prompt.