There's certainly plenty of stuff that's been written about supposed Trump-Russia links, much of it bizarre, contradictory, lacking in evidence, and even verifiably false but still widely believed anyway. Secret communications with Russia via a server in Trump Tower that looked remarkably like hotel junk emails from a server in a data center on the other side of the country from there, bizarre claims involving prostitutes paid to piss on hotel beds, liftings of sanctions and pro-Russian changes to the Republican platform that didn't happen (but few saw or cared about the debunkings)...
Basically we're looking at Trump being connected to Russian mafia for all his financing as well as Putin bribing him with 19% stake in the Russian state oil company for removing sanctions, as well as assisting with his campaign by hacking into the Podesta emails, sorta like how there were Watergate DNC office burglars.
Did you want all this in writing from Trump and notarized that he did this? Because that's not how it works. His job is to say he didn't do this.