Digital Terrain Model

Hello, I am new to Dronedeploy and cannot find an answer to my question:

I am planning to use the (paid) Digital Terrain Model App in the Elevation Tool Box to export my map as a Shapefile digital Terrain Model.
I am stuck as to which EPSG code I should use (google map 3857 vs. 4326 vs. the code for my specific map region) and which Contour Interval I should choose. I want a 0.25m separation of the Contours, but I cannot find what unit the Interval is in. There is no information on this in the documentation.
Please help.

It depends on what you have your units set at in settings. Also, what they are set at in DJI. Wgs84 images load into Google Earth natively. You can look at spatial reference. Com to find your local coordinate system.