Ah, OK.
You are correct; Mueller was given broad latitude:
The Special Counsel is authorized to conduct the investigation confirmed by then-FBI Director James B. Comey in testimony before the House Permanent Select Committee on Intelligence on March 20, 2017, including:(i) any links and/or coordination between the Russian government and individuals associated with the campaign of President Donald Trump; and(ii) any matters that arose or may arise directly from the investigation; and(iii) any other matters within the scope of 28 C.F.R. §600.4(a).