From the July 30 update forward, the app downloading format will be changed in the following way:

Pre-update
The game would download all required data before starting.
Post-update
The game will download all required data after starting.

Due to this format update, displayed file size requirements will be smaller when installing the game. Note that because the download will commence after the game starts, you will need more than the amount of free space displayed before installing. The smartphone versions of the game (Google Play, iOS) require around 1.2GB. The Steam version of the game requires around 2.8GB. The total amount of required space is about the same as before these download format changes.

Thanks for playing,
Shadowverse Team