I need help from the administration

Unfortunately, it's not possible to access the server folder. You can only download / upload one map as of now.

Maybe in future, but we can't guarantee it.

Quote from TevoGamers

I'm in trouble, can you help me?
I can not select more maps on my server because I can not access the folders of my server

If you are trying to add multiple worlds to your server, I may have an idea on how you could do it using the multiworld plugin
I have not tested this, but I think it should work

1.upload a world to your server
2.get the multiworld plugin
3.start the server
4.create a new world (superflat would generate the fastest)
5.somehow swap the names of the two worlds (I don't know how you could, but If you figure out how to then it should work)
6.upload a 2ed world
7.start the server to see if it works (you should have the first uploaded world and the 2ed)
8.repeat steps 4-8 till all worlds have been uploaded to the server

tip about the multiworld plugin: you can put a command into a command block "/mw move @p (worldname)" to allow players to travel between worlds from a spawn area (without needing to be "/op"ed)