As we are working with big clients that are very protective of their brand, it is important that you only use the assets that we supply to you in your assets pack.
Another reason that you can not use any external assets is that they often require any commercial uses to reference the creator. We cannot do this so please do not use any!
If there is an extra asset that you think would really bring your idea to life then please do not hesitate to ask us for it (this could be things like textures or vectors). That way we can be sure that the correct legals are taken care of and the brand is happy with it 👌