Sounds like you are either getting confused by the RTPs or you've got an old version of the RTP installed.
This game is made in RPG maker VX Ace so it needs the VX Ace RTP, a game made in RPG maker VX needs the VX RTP likewise for XP, 2000 and 2003. 5 different versions of RPG maker, each requires its own RTP (technically 2000 and 2003 have 2 different RTPs each but thats going on a bit of a tangent)
Get the RTP from here and install it:
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If you do turn out to have the VX Ace RTP replace it with a fresh install.