I agree with the above comments. As with any pet but especially with ferrets, a bigger cage is always better. Ferrets will get bored and destructive in a small cage, and may even become depressed. Their enclosure needs to have lots of space and multiple levels. Many ferret owners use the Ferret Nation cage (the double unit, not single). I fashioned a unique enclosure for my 3 boys by taking the side panels off of two Kaytee ferret tower cages and zip-tying them together. It works very well for us, and I saved some money by buying the cages secondhand.
Also please keep in mind that your ferrets will need about 4 hours of playtime outside of their cage every day, and 2 hours of that should be spent interacting with you. It’s great if you have a room you can dedicate just for them, but if not, you can ferret-proof another area of the house for their supervised playtime.