Ventilation is always beneficial and leads to a healthier home. However, the unit is designed so that after running for a while, the conditions in the basement will become drier. Therefore, if you don’t have AC upstairs, you know that there are days that are very hot and humid.
On those days, the basement may also still be humid. You will occasionally need a dehumidifier running for a few hours on those extreme days. The longer the unit is in, the drier it will become and you won’t have as much of a need for the dehumidifier.
Please note that the main floor conditions play a huge part in the basement conditions. Example of this is 50% and 72F on the main floor will reflect about 52%-55%/70F-72F in the basement.