观察．类推．条理化：分析性的英语语法（下册）
由 汤廷池 编辑
https://reurl.cc/XGqWxa
I have no idea where the writer of that text got the idea that "so that"
means "on condition that". Both example sentences they gave are nonsense.
They should have used "as long as" (some people in the UK use "so long as"),
or "provided".
As long as it's done, it doesn't matter who does it.
As long as it's been done, it doesn't matter who did it.
Provided it's done, it doesn't matter who does it.
Provided it's been done, it doesn't matter who did it.
The second example sentence in that link should be "You may go where you
like, as long as/provided you are back by dinnertime".