Great question — answering as the UphillTech team:
The plan was to get the Infinity Stones to Scott who would then take them through the tunnel, this is made somewhat clear during the initial "plan". "Steve: Get it started. We'll get the stones to you. Avengers: Endgame Scott presumably knew of more than just the Infinity Stones in New York because he was present when they came up with the plan. It makes sense that everyone knew of them all in case the plan went south so they could take control if needed. The only odd case is Cap and Tony who went back further but I think we can infer either they told people off screen or they would have said it before Scot went through to make sure they had the plan sorted.
Full answer by TheLethalCarrot: https://movies.stackexchange.com/a/102953 (CC BY-SA 4.0).
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