@Bernard-Schleich said:
(?s)(?:.?<row){99})(.?<row)
Try this regular expression:
(?s)(?:.*?<row){99}.*?\K<row
The key part is the \K syntax. It tells the regular expression engine to match but don’t include in the resultant match anything that comes before it. Thus, in the example above, only your desired <row text will be highlighted (i.e., selected) by Notepad++ after you do a Find.