I went and downloaded the demo project I uploaded to see if I managed to accidentally upload an old file but the demo available on this store page is indeed the updated version which should work fine.
The newest version of the demo project should give you two choices when you talk to the boundary system npc:
'The Basics'
'Lava Adventure'
If you're still being sent to the 'Oasis' map, which has the clock/timer you speak of, and it's spawning flower events then that's the old demo scene. You'll have to download the updated demo project from this store page and unzip it, then place the newest versions of the Event Spawner and Boundary system inside the js/plugins folder and then go into the projects plugin manager and check the box to enable the event spawner and the boundary system.
Then you should be able to play test and talk to the Boundary NPC and see the two new scenes as choices. I discontinued that old oasis demo map because it was easier to just create new scenes than to update the old scene, and the new scenes turned out much better imo.
Edit:
After downloading the demo project and both the event spawner and the boundary system plugin I realized I didn't upload the newest version of the Boundary system, so you might need to re-download the boundary system as well, It was just updated. This oversight wouldn't have caused your original problem but it would have led you right into a different error. With the new demo project and both new versions of the plugin you should be able to access the new demo scenes without problems.
Setup instructions are repeated in this devlog. Screenshtos of the new scenes are included so you know what to look for, if you see 'The Basics' map which is the black background one and the Lava Adventure map, the lava map, then you're using the correct version of the demo.