Hello @Corey Cheever ,
Thank you for posting here.
I am sorry, after my research, the download link of Microsoft Active Directory Topology Diagrammer is not available.
You can run command below to check AD Topology.
repadmin /showrepl * /csv >c:\repsum.csv
Shouldy you have any question or concern, please feel free to let us know.
Best Regards,
Daisy Zhou