Can you first try to stop the services?
sudo /opt/bitnami/ctlscript.sh stop
And then try again? If that doesn't work, it's most likely the system apache that is running. can you check PID of the process that is running on port 443?
sudo netstat -tulpn | grep 443
You can kill it with the following command:
sudo kill -9 PID
Replacing PID with the PID number from the netstat command. After that could you try to run the lego command again?
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