In object mode, Select mesh and armature, Right click Parent clear parent leave visual trans
Then on the mesh in object mode object properties add a modifier that’s the little wrench icon choose generate remash voxels
Add modifier deform armature for the object put the armature in that spot and for the vertex group at the group Of bones
Then an object mode in order select armature then hold shift and also select mesh, Then click control and p, parent with auto weights.
That is basically it
When you export it make sure that you have the mesh and the armature both selected.
Also when using modifiers you have to make sure to apply them.