It is recommended to install it for free through itools. Take the installation of Monument Valley as an example. You need to pay for downloading from the apple store, but installation in itools is completely free. The details are as follows:

On the computer Download an itools on your computer and connect it to your mobile device after installation;

Enter the software you want to download in the search box in the upper right corner;

Click Install in the search results that appear to download the software (As shown in the picture), it will be automatically installed on the device after the download is completed.