Current questions and answers regarding the map editor.

2) In the map properties tree: go to Objectives, select Primary (main objectives), Secondary (secondary objectives), then you will see Common (general) and PlayerSpecific (for a specific player; here you need to choose which one. Note that the player ID here is one less, i.e., the first player is, for example, zero, and the eighth is seven).
3) How many players are on your map? If there are none or only one, you won't be able to play.