Ouch, that is a huuuuuge material.
UE4 basically supports up to 4096/4096 (but can import 8192x8192, but will only mipmap to 4096).
So the only wayto get this done properly is to probably cut the texture up to 8192x4096 (or 4096/4096) textures and apply each section correctly/seperately.
I do wonder why that resolution is needed though, I could understand it for archviz, but a texture that size is so huge that no gpu can load it in one go. (Heck I just checked, and not even photoshop wants to save it in .jpg or .png.