Question

• Where the runtime distribution can be obtained? 
• How to install it correctly? 

Answer

• FineReader Engine 12 does not have a separate Runtime distribution, the components are provided with the same download as the Development distribution.
  The newest version of FineReader Engine 12 for Windows could be found here:
  https://www.abbyy.com/finereader-engine-downloads/windows/
• The Runtime components are installed from a separate installer provided with a Development distribution as shown in a screenshot below. 

The Command Line Interface should be used for installation. If you run it manually, the following message will appear:

The installation procedure is the following:

• Use cd command to navigate to the folder where the installer is located
• Run the following command specifying your installation path instead of "C:\MyFolder" 

installRnt64.exe INSTALLDIR="C:\MyFolder"

Also, there is a point in adding the following argument to the command since it may help avoid issues with registration. 

RegisterCOM=Force

More command line arguments can be found in this documentation entry: Command line installation options.

The Runtime license will be needed as well to use this distribution, it is usually provided in the same email as the Development license, depending on the type you may need to activate the license, the sequence is described here: Activation.