The pattern calls for 300 yard of the main color and 150 yards of a contrast color. You can easily make the bag deeper, by continuing in pattern until you get to the height you like (or run out of yarn!).
The pattern includes a small chart for the 4 stitch repeat that creates the zigzag motif.
This is a good pattern to try if you’ve never done any color work, its knit in the round, and there’s no shaping.

Size 7 16” circular needle suggested.