You can place an Asset Pack file in any folder, however, we recommend placing these files in the folders dedicated to the game assets, for example: assets/pack.json.
You usually need more than one Asset Pack file: at least, one for the Preloader scene and another for the rest of the game scenes.
Sometimes, you need to use “helper” assets in the Scene Editor, assets that you use in the Scene Editor as a reference but are not included in the game. You can group all these assets with their own Asset Pack file in a separate folder, and exclude the folder from the game build.
This could be the structure of your project:
assets/
preload/
preload-pack.json
... # preloader assets
levels/
levels-pack.json
... # level assets
helpers/
helper-pack.json
... # helper assets
The Asset Pack Editor searches for files inside the folder containing the Asset Pack file, and you can make it more effective if the structure of the project is well organized.