Adding the defaults in addition to template, switching YOUR_DOMAIN to {{ matrix_domain }}, and giving example of the two combined, as the playbook gives a warning about things being defined twice, so only using the last one in the vars.yml
You may wish to look at `roles/matrix-bridge-mautrix-facebook/templates/config.yaml.j2` and 'roles/matrix-bridge-mautrix-facebook/defaults/main.yml' to find other things you would like to configure.