How to make a script run when a file is opened in Illustrator?

Hello!
I have the below script that I'd like to run when I open a file. I tried saving it in the "Startup Scripts CC" folder instead of the scripts folder in Presers; however, I get the error window (attached) whenever I start up Illustrator. I can click on the OK button to continue, and the script works fine but would like to know if there's any way to prevent it from popping up. Can I please get help?

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docRef = app.activeDocument;
app.coordinateSystem = CoordinateSystem.ARTBOARDCOORDINATESYSTEM;

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function fileInfo(){
var pagesnr = docRef.artboards.length; // number of artboards

for (var i = 0; i < pagesnr; i++) // loop thru all artboards

{
//Get sizes of the artboard

var artboard = docRef.artboards[i];
var aRect = artboard.artboardRect;

//Artboard parameters as variables
var aLeft = aRect[0];//left site of a page
var aTop = aRect[1];//top of a page
var aRight = aRect[2];//right site of a page
var aBottom = aRect[3];//bottom of a page
var aWidth = aLeft + aRight; //width of a page
var aCenter = aWidth/2; //center of a page


//Text Justification
var center = Justification.CENTER;//Justification center
var left = Justification.LEFT;//Justification left
var right = Justification.RIGHT;//Justification right

/////////////////////////////////////////////////////////////////////////////////////////////////

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//FILE NAME
var fileName = docRef.textFrames.add();

fileName.contents = app.activeDocument.name;//File name
fileName.position = [aLeft + 0, aTop + 15];//position in a page

//FILE NAME Style
var nameStyle = fileName.textRange.characterAttributes;
nameStyle.size = 12;//size in punkt
//nameStyle.textFont = textFonts.getByName("Avenir-Book");//the font
nameStyle.capitalization = FontCapsOption.ALLCAPS;//ALL CAPITALS

//COLOR
//nameStyle.fillColor = makeColorCMYK (20,77,36,8);//color in CMYK
nameStyle.fillColor = makeColorRGB (255,255,255,8);//color in RGB

//JUSTIFICATION
//var nameparagStyle = fileName.textRange.paragraphAttributes;
//nameparagStyle.justification = left; //Justification



}
}
fileInfo();

/////////////////////////////////////////////////////////////////////////////////////////////////

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//FUNCTIONS
//RGBColor
function makeColorRGB(r,g,b){
var c = new RGBColor();
c.red = r;
c.green = g;
c.blue = b;
return c;
}

// CMYKColor
function makeColorCMYK(c,m,y,k){
var ink = new CMYKColor();
ink.cyan = c;
ink.magenta = m;
ink.yellow = y;
ink.black = k;
return ink;
}

//Get date
function getDate(){
var today = new Date();
var date = today.getDate() + ' / ' + (today.getMonth()+1)+ ' / ' +today.getFullYear();
return date;

}

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