I had already looked at section https://api.windy.com/point-forecast/docs.
If I understand correctly it allows to download numerical data, not graphic widget. Is that right?
We would also like to interface forecast maps (but in this case the documentation is clear)
It is Unix Timestamp, provided with 4 extra digits after the second unit digit (i.e. values are in hundreds of microseconds, instead seconds as expected).
Try 1601629220 instead 16016292200000 in any timestamp to date converter (e.g. here): you should get "Friday 2 October 2020 09:00:20"