Because the compression is so heavy, your computer has to do a lot of "heavy lifting" to unpack the files.
Here is a "solid post" style overview of what this download package offers and what you should know before installing it: Game Version: v1.04.79 (based on the CPY ISO release).
6 total, including the Episode Shadow add-on and various costume packs (Sega/Atlus pack, etc.).
You need 17 GB of free space for the final game, though you may need up to 34 GB during the actual installation process.
Around 40 minutes on an 8-core CPU, or up to 1 hour 20 minutes on a 4-core CPU.