The campaign and multiplayers are on different exe's, but the menu for choosing which chapter is on the multiplayer. So if you pick the wrong chapter, what you do is:

1) boot the multiplayer client
2) choose a chapter and the game reopens the singleplayer client
3) you notice the mess-up and re-switch to the multiplayer client
4) you choose the correct chapter on the multiplayer client
5) you go back to the single player client.

Very inconvenient, very politely put.

Made me install a malware called Ubisoft without my consent.

Came for the thicness, stayed for the thicness.