This guide assumes you have used the "Server - Install New Server" SOP to physically install the new server and add to domain. Do not make the terminal server a domain controller or transfer FSMO roles to it as it is not secure to do so.
Before installing the RDS role, you can install any software using the normal route. After you install the RDS role, the server must be put into install mode before installing if the software needs to work with RDS.
Open Server Manager, click "Add Roles and Features". Click Next, select Remote Desktop Services Installation, click Next. Select Standard Deployment, click Next. Select Session-based desktop deployment, click Next. Click Next, click the right arrow to move the TS server over to the right to select it as an RD Connection broker server, Click Next. Do the same for the RD Web Access Server, click Next. Do the same for the RD Session Host server, click Next. Check the box for "Restart the destination server automatically if required" and click Deploy. The server will reboot once complete. Once rebooted, login and click close on the add roles and features wizard.