You'll need to up the Transparency Light Paths under Render Settings. When I place a Jeffrey Pine, I'll set the Transparency Light Paths to around 64.

As with all of the Infinite Builder shaders, the Infinite Wood Builder is for Cycles only, Eevee doesn't like complex node setups. I'd avoid testing this theory as it's possible it will grind your system to a halt! The same applies to the Material Viewport shading.

All updates will be free for life to anyone who has purchased the ITB. I will be adding to the catalogue over time, I rather enjoy making trees and there's a lot more to be made. Once I finish them, I'll make them available in the downloads section and it'll simply be a case of dropping the preset into your sapling preset folder as detailed in the readme. The IWB will also receive improvements and additional features over time.