Did you check out my post about adult hosting companies? HostGator is not good at all and you can read many bad reviews about them on different forums: https://mradultaffiliate.com/adult-web-hosting/. Basically, they have a very poor support and they try to upsell you their different services that you do not necessarily need. There are many plugins that you could use, try to search for membership plugins or something like this on the WordPress: wordpress.org/plugins/search/membership/
You could look for them on the Google and there should be some good recommendations given.