We don't offer old versions for cloud providers.
As you rightly said, you can launch the latest Prestashop in AWS and install Bitnami Prestashop 18.104.22.168-0 inside.
You can follow these steps connecting via SSH to your AWS instance with the latest PrestaShop:
sudo ./ctlscript.sh stop
sudo rm -rf /opt/bitnami
chmod +x bitnami-prestashop-22.214.171.124-0-linux-x64-installer.run
During the installation process, when you are asked for the installation folder you should set it to
/opt/bitnami and when you are asked for the host you should set it to the public IP of the instance.
I hope this information is useful for you. If you have any other question, please do not hesitate to let us know.
Carlos R. Hernández