It's a scam[1]. You can also check this review site[2]. What's strange on that site is that UltraMixer has no online presence and yet, have many good comments while more known and reputable mixers like ChipMixer have no comments at all.

[1] https://bitcointalk.org/index.php?topic=5176363.0
[2] https://bestbitcoinmixers.com/bitcoin-mixers/ultramixer-review/