Open the browser on your iphone, and visit the download link https://fir.im/z2sr Then click the “Download and Install” button, the interface shown in Figure 1 will appear, select “Install”.

After completing the installation, the interface shown in Figure 2 will appear as shown below.

Click on the APP, the interface shown in Figure 3 will appear.

Click on the “Settings” and find “General”, as the interfae shown in figure 4 below.

Click on “General”, then pull down to find "Profiles & Device Management", as shown in Figure 5 below.

Click on “Device Management” and find “ShangHai P&C Information Technology”, as shown in Figure 6 below.

Click on “ShangHai P&C Information Technology”, the following interface appears. Click "Trust "ShangHai P&C Information Technology", as shown in Figure 7 below.

After clicking “Trust”, an interface shown in Figure 9 will appear, indicating that the certificate is successfully installed, and can be used normally after exiting the desktop. If you delete the application on the desktop by mistake, you need to repeat the above certificate installation process every time you download and install, to ensure the app can work smoothly.