No VST Folder, Windows

Hey there, I am a newbie and got some questions. So I installed iPlug2 and Reaper with this 02_Getting_started_windows · iPlug2/iPlug2 Wiki · GitHub documentation. But if I now try to compile the example project I get “The following effects were in the project file and are not available. REAPER will keep their configurations, but things may not sound as desired.
Track 1: VST3i: IPlugInstrument (AcmeInc)” this Message. So I go to C:\Program Files\Common Files, and theres no VST3 Folder. I thought if I create one and put the file in it my Problem should be solved but it is not. I think I may forgot to install something but i am not sure of, because I am very sure I followed the Instructions correctly. Some help would be great, thanks in advance!

How did you get IPluginstrument into the Reaper project file in the first place if it doesn’t exist in your VST3 folder?

Make sure, “you may need to give yourself write permissions for your VST3 plug-ins folder” otherwise the plugin won’t compile/save there.

I set up iPlug2 like explained in the instruction on GitHub, thats where i get iPlugInstrument and if i open the .cpp and compile it reaper opens. The Problem is there is no VST3 folder and i dont know why. where is the point the vst3 folder gets created?