Do you think that Congress would have not given him the powers to raise troops?
I don't think they would have looked favorably on his sending an armed force to Fort Sumter. Some in Congress would have, but many would recognize it as an act of war to send an armed fleet into South Carolina's territorial waters. Prior to the adjournment of the Senate, the Administration had been putting out the story to the Southern Commissioners in Washington and the Governor of South Carolina that Fort Sumter would be evacuated. As soon as the Senate left, Lincoln took action counter to that. The Southern Commissioners denounced the perfidy of the Administration when they found they had been lied to.
Lincoln felt the Constitution gave him the right to do what needed to be done first and then give Congress the opportunity to support or reject what he had done.
In other words, he snookered Congress. Some of the things he and his Administration did were things that Congress did not have the authority to bless.
As for Fort Sumter, Congress had nothing to do with that.
That was U.S.property and Lincoln was in his right as President to send the fleet to protect it.