Compiled via the Lichess Elite Database. These are the games played at Lichess that ChessBase 16 considers “strong games”. My best guess is that means avg. 2400+ and at least ten moves.
Includes blitz, rapid and daily time controls, with bullet games filtered out. Each ZIP archive contains one CBV, which is roughly the same size when uncompressed. (Everything here goes in a zip file.) That CBV, in turn, is a ChessBase database archive, and when opened will uncompress into a CBH and associated files, which also comprise roughly the same size. (This is the way.)