When you first boot the Cobalto V7 image on your Pi 3, Recalbox will automatically to fill the entire 64GB card. Do not manually resize partitions; let the first boot do it. The initial boot will take 2-3 minutes longer than usual.
The download is compressed to about 18GB. Extract it using 7-Zip. Cobalto V7 - 64gb - Recalbox 8.1.1 - Raspberry Pi3 Download
Includes the ArtFlix-Cobalto theme, with over 98% of games featuring scraped metadata like covers, videos, and marquees. When you first boot the Cobalto V7 image