The big problem with all these S4 clones is that there's just so many. Unless you've got a popular clone, it's very difficult to know which firmware is for your phone. If you're quite sure it's the proper firmware, then there's little to worry about. Regardless, as Pufferaway said, make sure you have a backup prior to flashing the new firmware.
On a side note,
[Only registered and activated users can see links Click here to register]. The one you linked to is for genuine Samsung s4. Though MTK phones should soon start to see Cyanogenmod firmwares, since they went commercial and are trying to expand their user base.
I'm trying to say this as light as possible. Next purchase you make, try to make sure you buy a popular, well known China brand, so stock firmware will be easy to come by, you'll have lots of options for custom firmwares, support to patches, and access to replacement parts should you need them. I'm not trying to down you, just giving advice for your next China phone purchase. You and your questions, no matter how basic, are very welcome here. Thanks for posting.