Actually, you need to change path directions for inner "cut-out"-shapes.
For less complex svgs you could use javascript to do this programatically as described in this related question "auto colour fill when Generate Font from svg figma icon using icomoon"
In your case - you need to do this manually.
Use a vector editor like inkscape (or Adobe Illustrator).
First you need to remove unnecessary elements like the image caption.
The caption would be way too tiny in a glyph/character.
Open your svg in inkscape.
Run these Path operations:

- select all
- Path / Break apart
- Path / Exclusion
- save the svg

