Can someone help me figure out how to make the auto start not stick or glitch in the first 3 scenes?
The glitchy auto start is due to more generic problem with low frame rate in this scene. The reason for the low frame rate is the large number of objects. In the scene there are 12950 object. Shapespark automatically merges objects with the same material that are close to each other, and usually this merging is enough to reduce the number of objects to be in 100-500 range, but in this scene, perhaps due to large number of materials (600), after the merging there are still ~7000 objects.
Most often the reason for such large number of objects are plants where each leaf is modeled as a separate objects, so removing/replacing such kind of models will help.