Welcome to the PLCTalk forum community !
Of course it is best to have or get some experience with ControlNet configuration and the basic getting online and scheduling the network functions before working on a system that relies on ControlNet. Since you're a new user and your posts were brief, I can't tell if you have the relevant experience and are asking a pure compatibility question.
RSNetworx and RSLinx changed under the hood along with ControlLogix major firmware v21, so mixing software before and after that big change is not recommended. For example, RSNetworx v11 won't work properly if you have also installed Studio 5000 v21, because Studio also quietly installed the new-under-the-hood RSLinx Classic 3.51 or later. It was a big hassle in 2014, and there's a fairly detailed list of products that you could break with that mix in RA Knowledgebase document
PN785 (Access Level Everyone).
So if you've got RSLogix v19 and nothing newer, I recommend sticking with RSNetworx for ControlNet v11 and RSLinx Classic v2.59.
If you have Studio 5000 v21 or later also installed, or RSLinx Classic 3.51 or later also installed, then go ahead and get the latest RSNetworx you can. It should link the *.XC project files with the *.ACD project files just fine, and will certainly support all the modern and legacy ControlNet stuff back to the PLC-5C1.5 and ControlNet 1.5 FLEX and 1771 adapters.
As for "where can I download it", you need a TechConnect contract and a software license to get it from the Rockwell Automation
Product Compatibility and Download Center. If you don't have a license, get in touch with your local RA distributor or field sales office.