To make the sum of the middle row be 6 the center entry must be 2. Then, to make the sum of the middle column be 6 the entry in the center of the first row must be 2. Thus you have
Now look at the first column. Either the top entry is 2 or the bottom entry is 2. Suppose that the top entry is 2, then the bottom entry must be 0. Hence you have
At this point you can't complete the puzzle. If the bottom right entry is 4 to make the bottom row sum to 6, then the diagonal sum is 8.
The only choice you made was putting a 2 in the upper left corner. Thus, suppose that the 2 is in the bottom left corner, then the top left corner is 0 and this time you can't fill the top right entry.
Hence the array you started can't be completed to satisfy the conditions given.