Just upload all the files to your HL2MP folder
(Default C:\Program Files\Steam\steamapps\USERNAME\half-life 2 deathmatch\hl2mp)

Download and install SDK-Hooks

just unpack the SDK-Hooks archive in the same directory as the Roleplay Mod.

Ready: the RP Plugin should work.

You need the Colors Addon and the SDK-Hooks includes for compiling.
You can get the colors addon from:

Just put the colors.inc in the addons/sourcemod/scripting/includes/roleplay folder. On Unix machines you have to rename the colors.inc to COLORS.inc
Also put the sdkhooks.inc from the package stated above in the addons/sourcemod/scripting/includes/ folder.