This is a memo on how to use Virtuoso, an RDF store.
Checking Registered Graph URIs
Conductor > Linked Data > Graphs > Graphs

Manually Uploading RDF Files
Conductor > Linked Data > Quad Store Upload

Enabling Federated Query
The following article was helpful. The “Account Roles” configuration was required.
https://community.openlinksw.com/t/enabling-sparql-1-1-federated-query-processing-in-virtuoso/2477
I hope this serves as a helpful reference.