The initial setup of the black pieces is wrong.
For the correct starting array swap the black Bishops with the Unicorns. Then you get the following arrangement at the Level D:
+---+---+---+---+---+
| u | b | q | u | b | 5 Queen Dc5; Bishop Db5, De5; Unicorn Da5, Dd5;
+---+---+---+---+---+
| p | p | p | p | p | 4 Pawn Da4, Db4, Dc4; Dd4; De4.
+---+---+---+---+---+
| | | | | | 3
+---+---+---+---+---+
| | | | | | 2
+---+---+---+---+---+
| | | | | | 1
+---+---+---+---+---+
a b c d e
Unfortunately also the Zillions file in 'raum.zip' copied this error.
The error does not occur at the old page for this variant: 'http://www.chessvariants.com/old.dir/3d5.html'.
See also the books:
Anthony Dickins: A Guide to Fairy Chess, and
D. B. Pritchard: The Encyclopedia of Chess Variants.