To investigate the issue, we need the Flexi server log and the PostgreSQL database log.
Alternatively, use the following Terminal commands, which will copy both logs to your Documents folder and package them into an archive called flexi_logy.zip:
cp /var/log/flexibee.log ~/Documents/
sudo cp /Library/Application\ Support/FlexiBee/Data/pg_log/startup.log ~/Documents/ && sudo chmod 777 ~/Documents/startup.log
zip ~/Documents/flexi_logy.zip ~/Documents/flexibee.log ~/Documents/startup.log
(You can find Terminal in Applications under the Utilities folder, or you can launch it via Spotlight by pressing the Command + Space keyboard shortcut. Simply type the word Terminal into the Spotlight search field and confirm with the Enter key.)