Appears it may be a mapping issue on the Start Date line item, likely you need to update the Custom Mapping on that field so that the format in the import is set to match the file. See screenshot below to illustrate.
Re: Level 1 Model Building SYS08 Employee Details Import Issue
Entirely agree with you as tasks is not always giving the right sequence of actions to do, so that we are facing with the same errors/system messages while following them. Thankfully, there are a lot of learners who has raised this issues to community in the past which I find really helpful!