The flashings have to be installed in a two step process.
The base of the chimney needs an apron flashing to extend down on the top of the shingles that will cover the Smart Vent and to also go up the face of the brick wall about 6 inches. The corners should be bent to fold around and up the sides of the left and right of the chimney.
The sides need the baby tins, aka as base step flashings installed under each individual shingle and butting up against the side walls of both sides of the chimney. Since you are probably very inexperienced with sheet metal, yuou shoud allow about a 2 inch fold of sheet metal to fold across the intersecting corners of the lower front side of the chimney.
The angled cuts need to be precise so as not to leave any open pin holes at the bottoms of the corners. Surface caulking is only temporary. The main water-proofing caulking should be inserted between the two pieces of sheet metal at the base of the corners prior to wrapping the metal and anchoring it.
The front base flashing and the side base step flashings will then need to be counter-flashed with an additional approximate 6 inch high flashing. This flashing will get anchored directly to the masonry surface. Once agsain, prior to anchoring the counter-flashings, a bead of polyurethane sealant such as Vulkem or Quad or NP-1 should be applied behind the sheet metal so as to get sandwiched in between the sheet metal and the brick surface.
You have to decide if you want to score out the mortar joints and embed the sheet metal into the chimney structure or to install a surface mounted flashing.
After the metal is anchored to the chimney with either Tap-Con masonry anchors or lead/zinc tap-in anchors, you need to apply a surface application of sealant on the top edgwe of the counter-flashings and wet finger trowel them down to a tapered profile to shed water down over the sheet metal.
It is harder to do than it sounds, if you do it right.
I will fetch a link to the NRCA Roofing manual for pictures which show what I described.
See pages 351 through 358. If you click on the Steep Slope Roofing section, you will be brough to that section and then look in the index to find flashings.