To enable script you need to add component Sciptable Auto Splitter to layout and choose script file in it's settings.

Script uses value which represents integer part of sync percent in the game - so depending on sync percent on some missions - some missions may not be autosplitted - you should then skip the unsplitted mission.

Second point to make is - when you quit from the game and start it again - autosplitter will always split. So if the game crash or you use Alt+F4 skip then you may need to undo incorrect split or add Alt+F4 skip as a split to the splits.

Third point to make is about starting memory S3M2 Between A Rock And A Hard Place - if you use the quit-load warp to get to the memory when if some amount of missions were 100% synced before - you may get a split during warp. It happends because in main game menu your sync percent is always 16% and you sometimes go to this memory with 15% total sync. This split is in splits in .zip file - but there are instances when you go to the mission with 14% total sync - then you need to skip that split.

The last split is manual - with the route that i use - and which is represented in splits file in the .zip - it's the only manual split in the game.