Sounds like the campaign needs time to gather the hard evidence needed to make their case and time is one thing they don't have.
At this point all Trump can do is request a recount. He has no access to any of the evidence, which are the ballots themselves.
The evidence of fraud will appear if the recount is done properly and evidence was not destroyed (ie. signed envelopes, etc).
The election cannot be certified before the recount is completed.