So I have this weird web where, when you enter, there's no scrollbars because everything but the cover page (covers the whole viewport) is hidden.

When you click a button called "Enter", the rest of the web gets unlocked and then, the scrollbar appears.

Thing is, I'm trying to catch some scroll depth tags in GTM (I got one at 75% of scroll) but, since there is no scrollbar when the web loades, they are instantly fired. Is there a way for me to enable these tags only when the button is clicked? Thx!