If you download the full set, start with these:

Approximately 7.9 GB (down from a raw 26 GB set by removing duplicates and clones).

A complete collection can range from 10GB to over 50GB; a high-speed MicroSD card is essential.

(Nintendo Submission Package) or a folder-based installation for custom firmware like Atmosphere, this collection utilizes the Final Burn Alpha (FBA) core to emulate golden-era arcade hardware. Key Features of the Collection Massive Library