How to make animation in unity Dots hybrid?

Update: There is now an animation package for DOTS which might work better than what is described in this answer, but is still considered highly experimental.

As far as I am aware, the machinima animation system with its convenient visual state machines and animation timelines isn't ported to DOTS yet. So you will have to program your own. My approach would be as follows:

1. Create a new shared component Animation which refrences the meshes used for all the different animation frames of an animated asset.

2. Create instances of that shared component - one for each asset you want to animate.

3. Assign those shared Animation component instances to any entities you want to animate.

4. Create a new system AnimationSystem which queries all entities with Animation, Unity.Rendering.RenderMesh and any components which are relevant for determining what frame to display (Maybe Unity.Transforms.Rotation to determine the direction it faces? Maybe Unity.Physics.MotionVelocity to determine if it's running or standing? Maybe a component of your own which handles the current state of your entity?).

5. Implement the system to use the data from the components to determine which frame to display, retrieve the mesh for that frame from the Animation component and apply it to the RenderMesh.mesh of the entity.

The DOTS Animation package is no longer usable and the next release isn't planed for quite some time. We have to go back to the Hybrid approach.

Here is a tutorial series that covers 1.0 and it's latest episode covers hybrid animation.