The (nearly) literal translation would be
When the tree has fallen, everyone will chop the wood
(not word by word, but retains the meaning)
What it is supposed to say is that when something big collapses or comes to an end (e.g. a company, a kingdom, someone's career) people will come and take the remains apart, scavenge what is left, make profit on the disaster (e.g. retract their shares from the company, divide up the kingdom, apply for the other persons job).
However, I have never encountered this before, so I guess it is a more regional proverb. The source might be helpful here.