I normally have a menu scene and use the StartGame() method called from a button to load the main game scene with the following script on a gameobject. If the menu screen has music or sounds then i would place a blank scene before the menu scene and have similar code a transition to the menu scene. This code loops until the bank has loaded.
public class Actions : MonoBehaviour
public void StartGame()
IEnumerator ChangeScene(int buildID)
yield return new WaitForSeconds(1);
Debug.Log("Master bank not loaded looping");
There is some documentation @ https://fmod.com/resources/documentation-unity?version=2.0&page=platform-specifics.html#html5webgl