sourdough starter splits
tl:dr; Do another batch.

It is not expected but not a full indication of a failure, but -  There is a lot of colours in the picture which is suspicious.  Also beyond vinegary after two days is suspicious. That kind of separation is indicative of the flour no longer having feed for their bacteria, which might explain the sour smell (not good). 

What kind of environment did you leave it in? covered and cold?

I'd try another batch. It should smell nutty and just a tad sour. You might just have been unlucky with the dominating bugs in your starter. 

Anecdotal:  I have had long-lived primers separate a little bit and brought them back to life with some careful feeding.