That essay demonstrates that Putin believes that Ukraine is closely linked to Russian civilization. That doesn't mean he believes Ukraine should be part of the Russian Federation, just that it should have close ties to it. The essay very explicitly advocates for the latter, and blames the West/NATO/"Nazis" for driving a wedge between the two countries.

(Of course, Putin's invasion has driven that wedge much further, and destroyed the relationship much more thoroughly, than the "Nazis" ever could. That's why I called him delusional)