As mentioned in earlier points. This addon is not designed for Eevee, and Eevee does not support all features. 

Even though we have attempted to make it all a little easier with Eevee, Eevees performance is totally reliant on what you have enabled, and what your system specifications are. 

We will NOT address any issues you're having using Eevee, as this is not the way True Terrain is supposed to be used. 

I am more than happy to reply to any, and all messages.

Please do not hesitate to send me a message here, and I will reply to you as soon as possible. Please send any screenshots of the issue you are having, and I will try my best to rectify the issue for you

Firstly, please check the version of Blender you are using. This product was built using 2.8x blender versions

You will need to enable the "experimental" option in the render tab (where you select CPU or GPU in the properties menu).

Once you have done this, the displacement will activate. The modifiers should automatically switch to 'adaptive', if not, then you will need to use the UI in True Terrain to enable the adaptive displacement

No!

You can use this for whatever you please; Commercial, Educational, or personal use.

The only limitations you have are:

• Do not make any amendments to the core files, rebrand, and/or sell as your own product/work
• Do not Redistribute or sell the Textures
• Do not redistribute/sell or give away in any format (websites, file sharing platforms, hard copies etc)

You must use real-world values when using this addon, you will need to scale your meshes correctly, and then apply that scale. 

If you're using smaller meshes, then it is advised that you do one of two things: 

1. enter the object in edit mode, scale it down, and then in object mode, scale it up and apply scale
2. use the displacement settings to reduce the amount 

This addon will* work with EEVEE, however it was never designed to be a realtime render addon. 

EEVEE does not support adaptive displacement, nor does it use the pointiness node, so the shader will be mapped a little less accurately using EEVEE. 

The particle assets, like rocks, trees and grass are all EEVEE optimised and so are the actual materials used in True Terrain, however as mentioned, the way these are procedurally mapped may look a little different, and you may find artifacts when adjusting some of the values for blending the maps.

I designed this shader, using the Filmic colour management system. This shouldn't have any drastic changes on how the overall product looks, but everything has been set up, using that colour format. 

This may mean that your renders may have 'blow-out' (over exposed areas) or be a little de-saturated if you're not using the Filmic colour management system

Yes

As I understand, you may use any image you render, as part of your logo or brand. I personally do not mind what you use this product for, provided you do not violate Blender Markets terms or the terms regarding the image textures and HDRi file.