It’s not a fraudulent story: I went and checked the FEC filings and checked the FEC document link.
What it is is a hit piece trying to throw shade on the Cruz campaign. RFAIs from the FEC are disturbingly common. So common in fact, they have a FAQ page! http://www.fec.gov/rad/FederalElectionCommission-RAD-RespondingtoRFAIs.shtml#why
(Is that enough acronyms for everyone?)
Again, I would very much like to hear the reason for this large donation, but none of this is illegal.