Tarkin is basically trying to claim that “He” is the mastermind behind the Death Star whilst it was not. Krennic has an outburst in front of all the Empiral War council about his achievements being stripped from him.
Krennic goes to Mustafa to visit Vader to assert his position as being the one “who made it happen” although Krennic relies on Galen.
Anyway Vader acknowledges Krennic’s situation but he sends him a strong warning to play ball with the chain of command otherwise he will be dead.
It is very important scene in establishing motive and chain of command and who are outsiders and who are in “the club” with the Emperor Krennic does not have that Luxury and is told to get back in line or his days are numbered.
Ultimately he and his advanced weapons research facility are vaporized in the mist of his failure. He got properly stitched up.