Right now CrowdRise is only set up for credit card donations, which are processed safely and securely by Network for Good and WePay. If you want to make a donation by check, the best next step would be to send your check directly to the benefitting charity.
The campaign admin can add this contribution to their CrowdRise fundraiser manually as an OFFLINE DONATION* as long as they can confirm that this donation was sent to the same charity that their fundraiser benefits.
Definitely don't hesitate to Contact Us with any questions.
*offline donations may not be enabled on certain Challenges or Events, in accordance with their rules