First of all, if you haven't already, you should do the Lite-C tutorial from beginning to end. Definitely play around with those sample scripts. It starts here:
https://zorro-project.com/manual/en/tutorial_var.htm

Second, there is no such thing as datetime in Zorro. If you don't understand the MT4 code you received, you won't understand how to implement it in Zorro either.

Read the MQL4 and MQL5 docs for reference purposes:
https://docs.mql4.com/
https://www.mql5.com/en/docs

datetime, defined below, works completely differently than anything in Zorro:
https://docs.mql4.com/basis/types/integer/datetime
https://www.mql5.com/en/docs/basis/types/integer/datetime

Finally, check out this conversion reference if you haven't already:
https://zorro-project.com/manual/en/conversion.htm