It promises "a substantial level of investment and a far-reaching business plan to take the Millers forward".
The previous owners had warned the club would go into liquidation if £1million wasn't raised by the end of the season.
Coleman said: "As a group we have invested a lot of money in the Millers - but I must stress we cannot do it on our own.
"Fundraising for the Save The Millers Campaign has gone really well and has undoubtedly helped us save the club. For the time being it is important the fundraising continues.
"We want to capture the spirit that has been generated by the fundraising across the Rotherham region. We have had a wake-up call, we do not want to get caught again."