You don't understand the startdates?
Take, for example, 20211012.1900
Let me stick some spaces in some helpful places:
2021 10 12 . 19 00
That better?
20211012 means 12th October 2021, and 1900 is in 24-hour clock format, IE 7:00PM
Stardates in the Star Trek universe work in an entirely different way. Wikipedia has a good explanation on how Stardates work.