Found the answer!
I had to create a .def file and put the exported callback functions into it like so:
LIBRARY ml-replay
EXPORTS
CreateAndInitMLReplayUploadTransaction
DelayCreationOfSimulatedClient
DelayDestructionOfSimulatedClient
DelayStartOfReplay
DestroyMLReplayUploadTransaction
FiniIdentifySimulatedClient
FreeAllUploadRows
GetDownloadApplyTime
GetNumRows
GetNumUploadTables
GetRow
GetUploadTable
GetUploadTransaction
GlobalFini
GlobalInit
IdentifySimulatedClient
ReportEndOfReplay