SCS has discontinued Scantron (OMR) Processing due to dwindling needs.
You can still use your department's existing scanners, or consider using Akindi, which is a modern and convenient alternative to Scantron. Plus, it's fully supported by the TU Blackboard team. See the Akindi self-help documents on the Blackboard Faculty Resources page.
Akindi allows you to set up an answer key online, and print out bubble sheets for your students to use. Once the students have taken the test, you can upload the student answer sheets by scanning them in and sending them to Akindi. Akindi will then grade the tests and provide you with a report, and can send the grades back to Blackboard for your students to see.