That depends on if the profile on Geni for your 2nd Cousin is claimed or not.
Does the cousin login to Geni? Then, you would need to login to Geni as your 2nd Cousin in order to link the profile of your 2nd Cousin to the results from FamilyTreeDNA.
If the cousin has accessed Geni from an invite, but has never set their password, then they are in a half-claimed state. This could be the source of the error you received.
If the cousin has never been invited to Geni, then I don't know why that error would show. You may need to be a manager of the profile in order to link it to FamilyTreeDNA.
So Jerry, which situation applies to you?