Rights to open a dialog for selecting a file

Thank you, I will definitely do it very carefully. I had seen this document before, but I didn't know as much then as now.

Ok, can I do it in DC Pro at the stage of development?
In the field properties I see this option but it's "gray" and I can't change it and that's strange to me.

I've read about Folder Level scripts, but this doesn't apply here. Namely, the forms are to be made available via the Internet to interested citizens and there is no question of any additional files in some folders and their rights.

Below is the entire code of the button handling the import. I would like to remember that in DC Pro it works as it should be.

var fld= this.getField("Plik");
fld.fileSelect = true; 
fld.browseForFileToSubmit(); 
var dataFile = fld.value; 
//tmpDoc1.closeDoc(true);

//var dataFile = "/D/Users/xxxxx/Documents/PDFy edytowalne/Test importu/dane.txt";
//var dataFile = "Dane.txt";

var tmpDoc = app.newDoc();

//tworzymy pola tymczasowe odpowiadające polom w dokumencie
tmpDoc.addField("PoleA", "text", 0, [0,0,100,100]); 
tmpDoc.addField("PoleB", "text", 0, [0,0,100,100]);
tmpDoc.addField("PoleC", "text", 0, [0,0,100,100]);
tmpDoc.addField("PoleD", "text", 0, [0,0,100,100]);

//definiujemy zmienne do pracy
var err =0;
var idx = 0;

while (err==0){
	err=tmpDoc.importTextData(dataFile, idx);
	if(err==-1)
		app.alert("Błąd: Nie mogę otworzyć pliku!");
	else if (err==-2)
		app.alert("Błąd: Nie mogę załadować danych!");
	else if (err==1)
		app.alert("Błąd: Brak danych!");
	else if (err==2)
		app.alert("Błąd: Użytkownik nie wybrał linii!");
	else if (err==3)
		app.alert("Błąd: Uzytkownik nie wybrał pliku!");
	else if (err==0){
		
		//pobieramy z pola w dokumencie tmpDoc
		var PoleA= tmpDoc.getField("PoleA").value;
		var PoleB= tmpDoc.getField("PoleB").value;
		var PoleC= tmpDoc.getField("PoleC").value;
		var PoleD= tmpDoc.getField("PoleD").value;
		
		//teraz przypisujemy wartości do właściwych pól w dokumencie
		this.getField("PoleA" + (idx +1)).value = PoleA;
		this.getField("PoleB" + (idx +1)).value = PoleB;
		this.getField("PoleC" + (idx +1)).value = PoleC;
		this.getField("PoleD" + (idx +1)).value = PoleD;
		
		if (idx==19){ //ta liczba w warunku jest o 1 mniejsza od liczby rekordów w pliku do importu
			err=-99;
		}
	}
	idx++
}
		
tmpDoc.closeDoc(true);

		

Above this code were comments that I removed. The second line in this listing is where Reader crashes.