Hey Olollo,
the native theme’s submenu in Ikebana is vertically aligned (i.e. one submenu item under another), and the theme does not envisage as ready horizontal submenu. Certain customization work, which is not covered by the ThemeForest support offer, will thus need to be carried out in order to implement this; I can recommend Envato Market as a source of knowledgeable WordPress developers who can take on ad-hoc customization tasks.
Sincerely,
Andrii / Satori Studio