1. No apple id: If you download from the appstore of your mobile phone or itunes of your computer, you need to enter an apple id to install it, otherwise you cannot download and install it. If you don't have an id, please register one first.

2. You can't install by downloading third-party software: If you download from third-party assistant software, it is recommended to use the AppStore of your mobile phone or the itunes store of your computer to download and install again.

3. There is something wrong with the installation package: for example, it is incomplete or the signature is inconsistent. At this time, you can try to download again and then install.

4. The storage space of the mobile phone is full: empty the memory of the mobile phone, delete the software that is not commonly used and try to install again.