Do I Need To Buy Separate Web Hosting Plans For Different Directories?

I have already purchased web hosting and a domain name from a local hosting provider but unfortunately, I'm not happy with their services because every night I receive notifications from Jetpack that my sites go offline every night so I want to migrate my data/site including all the directories to a reliable hosting company. However, on the same domain name, I have created 3 different directories or in simple words, I have installed WordPress on 3 different locations on the same domain name i.e:
1. https://grabhosts.net
2. https://fastcomet.grabhosts.net
3. https:/grabhostsnet/blog

All these directories, I have created using the cPanel where I had the function to create a subdomain for the subdomain such as fastcomet.mydomain and for the blog, I have created a simple folder in my domain files and installed WordPress on it.

So if I want to migrate my site including all the directories & WordPress installations, what should I do? Will the OVHCloud team help me with the migration? Will I need to just provide them my domain name/site log in details or do I need to do everything from my side?

And also since I have multiple directories on the same domain, do I need to buy separate hosting plans for every directory?

Guiding me on the process would be highly appreciated.

Stephen