This doesn't sound like a modded server, but more like a semi vanilla server. A lot of mods don't exist that do these things in forge or spongeforge which is for modded servers. In which case you'll want to learn how to install Spigot on the server. For plugins that do what you want, I can suggest Vault for economy, Grief Prevention for claim blocks, PermissionsEx for permissions and group managing, ChestShop for player chest shops OR ShopGUI+ for a global GUI shop, EssentialsX for kits/items on join, and FeatherBoard for the player UI on the side. Featherboard is like $10.00, but I believe there's also another plugin that also does the UI that is free called TAB. From experience, Featherboard is easier to use. You'll also want to install PlaceholderAPI to be able to use to placeholder for the player's money and the number of players online etc to use in the UI. All these plugins are up to date for at least 1.15.2. Teaching you how to install all these plugins would take a lot of effort and time that I don't have, but I can assure you that all these plugins have configuration tutorials right on the websites you can download them from, which is https://www.spigotmc.org/. You can also contact the plugin authors via DM or on their plugin discussion page if you need additional help. Another tip: whenever you configure a YAML file, never use tabs - always use spaces. When I first started out with server hosting, it took me weeks to find out what was breaking my configurations. You'll also probably want to download Notepad++ on your computer for easier configuration editing. It's like Windows Notepad, but easier to read. Good luck!
So, this may seem out of place considering I'm not looking to join but a way you can greatly decrease the amount of work for those looking to join the server is by using MultiMC. I'm not sure how familiar you are with it, but it would effectively allow you to output any changes necessary in a very clean manner, considering all players would really have to do is download any of the updates you make to the pack and throw it in their instances' folder without much hassle.
The most trouble they would have to go through is perhaps changing configs (which they can also just drag and drop config files provided) or even deleting certain files that you deem no longer fit for the server / pack.
If you're not used to using a computer through remote access, this might be a bit tricky for you, but if you do some reading it should work great for what you want:
Get the free tier, I'd recommend using the linux server and not the windows one, transfer the skyfactory files to it, make sure it has java installed on it (I imagine you'd need to add it), open up a port with IPtables, and figure out how Amazon treats their networking issues (I'm used to a home comp where it's important to make sure the router has port forwarding turned on, not sure how that would work in this case).
I bet if you search around you can find a guide on the internet specifically about how to set up a MC server using AWS. I could probably figure it out but I have never done this myself.