You can just use a Texture Coordinate nodes and set Coordinate Index to the corresponding channel. i.e. 0 in Unreal is 1 in Max, 1 in Unreal is 2 in Max, etc.
However, looking at what you are trying to achieve this wont work for you. Multi UV channels are useful for having different UV patterns and sizes so that you can apply noise and stuff to make the textures look more natural. In your case you are bound to have overlapping textures, which will look messed up like that. So you’ll need to use multiple UV channels i think.
You may need to shuffle the textures around, depending on the tiles that you used in your modelling package, but this should do it.
Do note however, that this is bad practice and what I’ve linked is workaround that puts four times higher strain on pixel shader, than using 4 separate materials. You should assign different materials to your mesh. There is no multi-tile texturing as you know it in UE4.
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