Hi @Rachel,
While we always welcome all users to use Certbot, and I hope that @stevenzhu gives you some helpful advice, users who have only administered their sites through control panels (or don't know how to access a command line at all) are really not the target audience for Certbot. Certbot is primarily aimed at system administrators who are already at least slightly familiar with using the command line.
For users who normally use control panels like cPanel, the best solution is to get Let's Encrypt integration inside the control panel. And in fact, cPanel has already provided this and most cPanel users worldwide now have access to Let's Encrypt support from directly inside of cPanel. It seems to be a specific decision on HostGator's part to continue not to allow customers to access this functionality, thereby requiring customers to use alternatives that aren't ideal for their hosting environments.
At a high level, since so many HostGator customers have had problems similar to yours, I would suggest that unless cost is your highest priority, you consider either paying extra for HostGator's preferred HTTPS implementation (which I think involves a different, paid certificate authority) or switch to a different hosting provider that provides Let's Encrypt certificates for you more easily—for example, by permitting you to use cPanel's built-in support.
Our community has identified a large number of hosts that are in this situation:
I realize that this list isn't particularly helpful for making a decision among hosting providers because it doesn't provide any other information about the hosting environment or plans, but hopefully it demonstrates that, when its customers want to use Let's Encrypt certificates on their sites, HostGator is leaving them in a more difficult situation than many other hosts do.
I mentioned this important problem above:
To me, this suggests that it may simply not be worth it to "fight" HostGator about this this way. However, an alternative that we mentioned above that isn't a command-line client is
If you can create files with specific names and contents on your web site, ZeroSSL can walk you through the process to get a certificate inside your web browser, and you could then provide that certificate to HostGator to install. But if you take this route, you'll still have to repeat this process at least every 90 days because the certificate will expire and need to be replaced with a new one.