You can use the "Enterprise Agent" installer to install the Backup Agent on Windows. The Backup Agent installer is a typical Windows installer application. Please download from below link
x64 -- http://repo.r1soft.com/trials/ServerBackup-Windows-Agent-x64.msi
Once you have the Backup Agent installed, follow the instructions given below to install the Backup Agent.
1) Log on to the Windows server asl Administrator.
2) Extract the files from the archive. Navigate to the directory where you saved the "Enterprise Edition" or "Enterprise Agent" installation file.
3) Double-click the file from the archive
4) Double-click on the package or right-click and chose "Install"
5) Wait while the files are extracted.
6) Choose whether to reboot now or reboot manually later. Backups will not work until you have rebooted the system.
7) The installation will complete on it's own.
8) Add the key to Windows Backup Agent
""In order to keep the Backup Agent secure, connections are only accepted from specified Backup Managers. To authorize a Backup Manager to backup the Server, you must first add a key of the Backup Manager to the Backup Agent. The Windows Backup Agent Configuration Utility allows users to add an encryption key that allows the Backup Manager to connect to the Windows Backup Agent.""
Adding the Backup Manager public key to the Backup Agent means creating a text file on the server (Backup Agent machine). The default directory is C:\Program Files\Idera Server Backup\conf\server.allow.
9) Run the Windows Backup Agent Utility.
10) The main window of the Windows Backup Agent Utility will be displayed. Switch over to the "Authorized Server Backup Managers" tab.
11) Click on the "Add..." button located on the right to authorize a Backup Manager.
12) The "Add Server Key" dialog will be displayed.
13)5. Enter the following information to inform the Utility how to contact the Backup Manager.
Filename - Enter Host name that will be shown in the "Installed Keys" list. The file containing Encryption Key will have this name
Protocol - Select "http" or "https" from the drop-down menu.
Server Backup Manager - Enter the IP address or DNS Host Name that the Backup Manager uses.
14) Click on the "OK" button.
Once this information is entered and verified, the backup manager will be contacted to find its Public Key and the IP address that it will use for outbound connections. During this process, the Windows Backup Agent Configuration Utility uses the current Backup Agent port settings.
If you have defined the appropriate Backup Manager properties, the Manager Key will be successfully added to the Backup Agent database and the requests from the Backup Manager will be allowed. The Key name will appear on the "Authorized Server Backup Managers" tab.