Download in the apple store of the mobile phone: Open the apple store of the mobile phone, click Search, enter the software to be downloaded, then select the software from the software that appears, click Get, and enter the apple id password to download (some software needs to be paid).
Download in itunes: When the computer downloads an itunes and connects to the mobile phone, it will automatically enter the itunes store page, enter the software you want to download in the search box, enter the ID and password to log in, and after downloading the two softwares, click Sync to the mobile phone on the right to transfer the software to the ipad (some softwares need to be paid).
Download through third-party software. You can download pp Assistant, xy Apple Assistant or 9 1 Assistant from your computer or ipad. You don't need to log in. Open the software, enter the desired software name, and then click Download and Install (appleID and password are required to open the software for the first time without jailbreaking).