Which installer should i use to add a server in LEM?
Depends on the server.
For Windows, you can use either the Local Windows Installer or the Remote Installer. The Remote Installer will run on another machine, and allow you to push the software to many clients at once.
For Linux, use the appropriate x64 or x86 installer.
You can find all the installers for the Agents for LEM 6.1.0 here:
SolarWinds Knowledge Base :: Additional LEM downloads for version 6.1
Retrieving data ...