https://www.krontech.ca/wp-content/uploads/2021/09/RE-PDEV-10009-Chronos-User-Manual-Full-Software-Version-0.7.0.pdf .
On Page 88 / 89 of the Cameras user Manual you can see the Option "Text Overlay" explained. This will add an Timestamp to each frame of your Footage when Saved as H.264 or TIFF Format.
If you want to preserve the Original Quality of the Clip and not use Advanced Software (there is a lot of professional Editing Software that can Add a timer, but thats usually not super easy to just do for anyone who has not worked with such Software before. If you still want to, look up some Tutorials about it on YT, there are Plenty, else i can also Link some, if you dont know what to exactly search for); you could easily just enable the Timestamp Text Overlay, save your Footage once with the Overlay /Timestamp, and then disable the Overlay, and save again "clean" without Overlay.
That would be a fairly simple way to do that in-camera, and even though it takes a bit of time to save everything twice, would probably still be faster or at least about as fast as having to edit each one of the Clips to add a Timer in An Editing Software, and then Also Render it.