The plugin is compatible with the ALS plugin, as the ALS characters have the same skeletal hierarchy as the UE4 mannequin.
Simply pick the ALS_Mannequin_Skeleton asset when selecting the retarget source.
See our Getting Started documentation for more information on the retargeting process.
The simplest method to use a Mixamo character with ALS, is to use live retargeting to copy the pose from the ALS mannequin to the Mixamo skeleton.
1. Create a new Animation Blueprint and select the retargeted Mixamo skeleton as the target.
2. In the blueprint AnimGraph, add a Retarget Pose From Mesh node, and in the node settings enable the Use Attached Parent option and select the ALS to Mixamo IK Retargeter asset generated by the plugin.
3. Create a duplicate of the ALS blueprint AdvancedLocomotionV4/Blueprints/CharacterLogic/ALS_AnimMan_CharacterBP to use for Mixamo.
Then open the new blueprint and add a new Skeletal Mesh as a child of the existing Skeletal Mesh component (called Mesh).
Setup the new Skeletal Mesh component with your Mixamo character mesh and select the Animation Blueprint created in step 2.
Now you can hide the ALS mannequin by selecting the Mesh component and uncheck the Visible option in the Rendering settings.
4. For testing, open the ALS_DemoLevel, delete the ALS_AnimMan_CharacterBP and replace it with the new blueprint. Then in the settings set the Auto Possess Player option to Player 0.
You should now be able to move around your Mixamo character with the ALS system.