Thank you so much for trying it out! Ha, glad you figured it out right after posting.
Please keep in mind that this tool is in VERY early stages, so I don't have enough yet to actually build a full game, but I hope you like the direction this is going. Yes the object placement is still unintuitive - I'm planning a full overhaul of the object system as soon as the Asset editor is more mature. You'll be able to place assets/triggers/spawns/particles etc both from the 2D and 3D view in the world editor.
Let me know if there's anything you'd like included, I'm always open to suggestions and feedback! In the meantime, I've released a 2nd devlog: https://bonnie-games.itch.io/bonnie-32/devlog/1315502/devlog-2-the-first-tree