@Ann you have a valid domain email address and valid domain to use AWS no need of SSL. And ofcourse you should book a domain and create a domain specific email id.
@Ann, SSL for IP addresses is possible but not very common. I highly recommend you buy a domain and request a SSL certificate for it. Without a domain, your landing pages will have an IP address and that truly is a disaster I think.
Yes, @Ann, this is how I would do it. Get a domain, redirect it to your Mautic installation, get a SSL cert, install it on your Amazon machine and configure Mautic zu use SSL.
Also, the SSL is at the server level if you use AWS, a VPS you can install an SSL on that level.
Just like @PeterTL said you need a domain but you also can create a CNAME record to give a Domain/Subdomain to the AWS IP.