You have to click on a keyboard, in left panel. Let the program to calculate the amount of data, and you will see which is the size of different types (wave size, parameter size, pack install data size).
As a remark, you will see a progress bar below that combo. That progress has some colors: black is the data which was packed already for an installation, green means it is a new data for selected keyboard, red means some data exceeded the available size.
Regards,
Vali