Super simple manual flipbook.

Say you want to manually animate a flipbook in matinee.
Here's a very simplified setup for it. The downside is: is has to be one single row but you can modify the amount of columns as you wish.

There could be less instructions but the idea is to make it easy to instance. In the material instance, you just have to modify the FramesAmount parameter and you can animate the FrameIndex parameter in matinee with everything working fine.

What's happening there?
You simple tile and shift your texture.

Tiling.

In this case, one tile is a forth of the texture size. So you divide 1 by the amount of horizontal frames in your texture and multiply only the U of your texture coordinates.
You've got the correct tile size.

Shifting.

To display the correct frame at the right moment, you'll just need to move the texture horizontally.
The amount by which you need to shift the texture to reach the next frame is one nth of your texture, n being th amount of horizontal frames. (4 in this case)
The FrameIndex value (animated from matinee) multiplies this to find how many times you need to shift it.

The floor node is there to ensure you only display full frames.
Since the frame index is floored, your index will be starting at 0, remember this when you control the value in matinee. To animate a four-frames texture, the value will have to interpolate between 0 and 3. (If your texture is set to wrap, a FrameIndex of four will get you back to displaying frame 0.)

Simple.
Not super clean or flexible but definitely super simple.