Because it is commercial software, you can't use genuine software without buying it.
There are many versions of K3 series. I suggest you download the 10.4 version, which is a very classic version. Even if you don't buy it, you can use it for 3 months for free. Enough to study.
Search "k3 10.4" on Baidu can be downloaded directly, but CDs can be bought in the computer city.