Based on what I’ve seen, that’s how it goes.

Capitalist is equivalent to economic-right.
Socialist is equivalent to economic-left.

Yellow and blue squares should both be ”capitalist”.
Green and red squares should both be ”socialist”.

USSR was communist, which is the authoritarian form of socialism. This is the red square.

The meme jokes about what people from the quadrants think which economic system the USSR followed: capitalist or socialist. Most people would agree that the USSR was socialist, except for people in the libertarian left quadrant.

The very authleft spectrum belives that real Socialism is what A certain Austrian painter did and the rest is Jewish propoganda

So, the authright square should be "Jewish propoganda"