I would doubt that fresh mango would last very long after slicing and would break down fairly quickly.
Their list of ingredients is what you should be following:
Ingredients: Pasteurized cow's milk, sweetened dehydrated mango (mango, sugar), crystallized ginger (sugar, ginger), salt, flavoring, rennet, dairy cultures, potassium sorbate, citric acid, sodium bicarbonate, sulphar dioxide as a preservative.
The sweetened dehydrated mango (mango, sugar) and crystallised ginger (sugar, ginger) will typically have some sort of preservative, eg Sulphur Dioxide, to make then keep longer.
Look in the supermarket for for packets of dried mango and crystallised ginger.