Hey.
I guess you’re trying to export the max object with the hair&fur modifier applied. That’ll indeed (and correctly) write a 3D mesh in the alembic file.
What you need to do is convert the hair/fur generated by the modifier as a spline, and then export that.
Try the “Hair → Spline” fonction in the hair&fur “tools” section.
That’ll create a line object which you can export as an alembic file and import as a groom in UE4.
Hope this helps,
Cheers,
T.