The mechanisms for "click-in" joining are varied. It's important to note that they are not resin-printer specific, although one should make considerations for the material from which the parts are made.
Some resin printed models will be brittle and would require that the click-in feature be constructed with minimal distortion, while others could be printed with more flexible resin and tolerate much greater distortion, but may also release more easily.
From a Pinshape site:
Note that in this image, the joint requires a matching spherical portion to accept the male portion. This is presented as a sample, not as a complete answer.
The upper most portion of the male segment is a cylinder of slightly larger size than the main body. The top of the cylinder has a taper which enables the receiving hole to force the sides inward, beyond the matching notch in the receiving hole.
The underside of this larger cylinder can be bluff, making removal difficult, or can be tapered to match, allowing for easier removal.
Consider that the cylinder can be stretched out, flattened in such a way that the cross sections of the male portion and the receiving hole are slots rather than cylinders.
The pages at hubs.com provide greater insight to designing snap-fit joints in 3D printing. The following image represents fairly closely the above dissertation regarding deflection:
Much more detail regarding design can be found on the linked site.