There's enough in their service description to not trust them.

The way the system is described, you encrypt a file on your device, upload both the key and the file to the cloud, then the receiver downloads both the file and the key.

Look at the diagrams here: https://www.virtru.com/how-virtru-works

The "encryption key storage" is central to how the whole thing works. It's also a dumb idea. The only thing I can think is that it allows a file to be delivered out-of-band, but the inescapable fact is that decryption material is available to at least one other party.