It depends on if you are making a new opening, say in the basement, or replacing a door,(see Seve).
A new installation or a replacement will still require the use of "Mollys" to last a lifetime.
Tapcon screws will work but, won't last a lifetime, (unless you are very old or sick).
Place the sill down and mark the holes, then with the proper size bit, recomended for the molly, drill the hole and insert the molly. Place the sill over the holes and screw.
Don't drill to deep if it's in the basement, water may leak through when it rains.
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