What FTP clients exist for the site?

Question

FTP

Good afternoon. The situation is stupid and I'm looking for a way out of it.
There is a ready-made site that needs to be uploaded to the customer's server. The site is one-page and it is enough to upload it to the desired directory.
The customer has people who deal with the entire IT part. Persons do not remember any access data to the server, they cannot make a backup ... in short, they cannot do anything and there is no hope to rely on them.
Now there are:
1. Access to a folder with an existing site, without access to the root folder of the server. And everything would be great, BUT, this folder is under some kind of rights and no matter what changes I make (even if I delete the entire site via FTP) - this does not affect the working site in any way.
Decision:
1. IT-specialists themselves will upload the new site to a separate folder. However, there are still some changes that need to be made on the new site. I don't have access to normal FTP.
I will use textolite as an admin panel. The admin panel allows you to navigate through the directories of the site. Allows you to download the required files. BUT, download - does not give such an opportunity.
Maybe there is a system that can be thrown into a folder with a site, and then go to the right address, enter a password, go to the right directories and make the necessary changes there, download/upload, etc.
Thank you.