How to take a backup for my symbols on my feed server? 

In order to take a backup for your symbols configuration from your server to your local PC so that you can save it at your side to be used later in emergency cases or use it in another feed server to avoid any situations that may affect feed's server.

1- Access your server and open the following path:
C:\Program Files\VertexFX Currency Server

2- Take the “Manage” file and save it in your side. To save any folder at your side, it is preferred to compress that folder and this by right clicking this folder, then select “send to” then select “compressed (zipped) folder” --> this folder will be compressed at the same path.

3- After that you need to save this folder at your local PC from your server… For any assistance in that, check this link: Copy files from server using RDP