On this page https://github.com/mongodb/mongo-c-driver
it points to the latest tar saying,
"The most current release is 1.1.5 which you can download here. " and points to here:
https://github.com/mongodb/mongo-c-driver/releases/download/1.1.5/mongo-c-driver-1.1.5.tar.gz

but it does not exist, i.e. a broken link