@MrKim
You say that you have the phone (the S7) - Well then connect it to your IDE, then go to the Designer, click on WYSIWYG Designer and then Connect.
Now look a the bottom left of your screen. You should see:
View attachment 61020
Now go to Variants and click on New Variant button. You will get this:
View attachment 61021
Enter those dimensions here (that is the 1080x1920x2.625 - or whatever your device returns) and press OK
You will get this:
View attachment 61022
and there you will see the dimensions required with a scale of 1 of your connected device. If you now press "Yes" - it will be added correctly to your Variant List.
I hope this short trick helps - BUT - out of experience - PLEASE listen to
@NJDude and
@Erel 's advice - it will save you much heartache.