Here is the link to the Absentee Ballot Application Web Portal from the Tennessee Secretary of State’s site. It lists the qualifications and instructions.
You can monitor the status of your request by using the HCEC Voter Request form:
Here is the Absentee By-Mail Ballot Request for the upcoming March 2, 2021 City of Chattanooga Municipal Election. Note that the last day to accept a Request is February 23rd, 2021.