Importing a Heightmap as a Landscape with matching texture

Ok, i used UE back in the Unreal Tournament days, so yes i am old. I was thinking about starting a project. I have some open world game in mind. i made a heightmap and a rough colormap for reference. My goal was importing the heightmap (that worked) and use the colormap on the landscape just for reference and paint it over later. I imported the colormap (same aspect but different resolution) as a material but get it to fit on the landscape is a pain. i think the biggest problems are booth are not square (i wanted the island wider), so the to maps are more wide than tall. but the colormap i imported acts like a square. If someone has a quick and dirty solution that would be great. as i wrote, i want the colormap just as a reference texture, so i see where i am (in game) and plan where to put villages and stuff.

Any rough, “import it that way/ use this to 99% align the color map” would be enough.

Cheers dudes and gals, any help would be appreciated.