Correct. You have to be able to put the focus in the field in order to scroll the text in the field and you have disabled that option in order to keep the field from being editable.
If this is FileMaker Pro, define a calculation field with text selected as the result type and put the name of this Notes field in as the only calculation term. You now have a field that cannot be modified by editing it which copies the exact contents of your notes field. Put it on the layout with scrollbars and Browse Mode access permitted.
If you need something like this for FileMaker GO, this trick pops up the keyboard even though you can't edit the field so this trick isn't the best option there. If you want scrollable read only text in FM GO, see this thread: Getting a simple "Read-only" scrollable field is now possible