Thanks for the information @tomas1.
Does this folder exist in your instance?
sudo ls -la /opt/bitnami/letsencrypt/certificates/
Could you please share the content of the cron jobs?
echo "Cron configuration of the root user"
sudo crontab -l
echo "Cron configuration of the bitnami user"
sudo crontab -l -u bitnami
Once we have all this information, we could help you to renew your certificate.