There should be little to no 'smell' to this type of insulation as there is a heat process that place the 'paper' in a neutral state. A noticeable odder. ,I would recommend taking it back. It is possible that it is treated with chemical to keep bugs from nesting in the product between manufacturing and use. Look at the location of manufacturing. It is not uncommon for China based product to have that chemical treatment.
This type of insulation is designed for placement in the area above ceilings and/or sidewalls. Under stairs would not commonly be recommended.
