The IB450SS and IB650SS ice makers use a gravity drain to expel the excess water. Neither of these units work as a freezer, so ice is constantly melting That melted ice needs to be drained away. Since these units do not have a drain pump, it is common for them to be installed where there is a floor drain present and gravity can do the work. However, if you do not have a floor drain present there are other options.
Most Hardware stores such as Home Depot or Lowe's carry what is called a condensate pump. This will take the water from the unit and carry it to a drain. A model we commonly hear being used is made by a company called Little Giant. It is a VCMA-20ULST. This or a similar model with the same 1/2 gallon capacity and 110V/115V power will work fine.
If you have not yet purchased a unit, EdgeStar does make a version with a pump built in. The IB450SSP will give you more flexibility as there is no need for a floor drain during installation.