The ideal Angle-of-Attack (AoA or alpha) differs depending on foil size and conditions.
If you select a join point, your foil will be inserted and rotated by the ideal AoA relative to the direction indicated by the Nose to the Tail line.

Tip: you can select the nose-to-tail line itself if you like - and if you do this, the foil will be rotated about its central moment (usually about 25% in from the nose)

Tip: If you want to join at the Nose or Tail point, you first need to add a second point on top of it (Fusion360 doesn't let our add-in select the same point in 2 different selection inputs)