Server Migration help

So basically I wanted to migrate a server from Minehut since there were noticeable performance decreases, so naturally I downloaded the world from the website and migrated in onto Aternos. However, when I loaded up the world, the Overworld was the same, but the Nether and the End have both been reset, and all of our builds were gone. I had this problem before on Minehut, but that was when I changed the server from Spigot to vanilla, and this was fixed just by changing it back to spigot. I believe that I missed some files during the migration, but I'm not entirely sure how to fix this problem. Can anyone help with this? Also, b4 anyone mentions, I already tried changing the server on Aternos from Vanilla to Spigot, and that didn't do anything.

so I saw that you upload the world_nether and world_the_end files, but i'm not sure where you upload it. Also, which server type should i use, since i saw you recommended paper over spigot to the other user

I see that there is one place to upload files, but when I upload new files it replaces the other ones? I think I tried this but got scared that the files of the overworld were replaced

its that the original files that I uploaded initially was the world files from Minehut, with all of the data like advancements and stuff, but when I upload the world_nether or world_end files, it completely erases the overworld files and replaces them with the uploaded files

Oh wait I actually didn't know it was possible to have multiple uploads like that since this is my first time on aternos. Can you explain how to have multiple like you show

Cool. thanks for your help