Look at the channel on both sides of the box opening, where the two tabs slide. You will see a cut out, half circle area, about in the top third channel of the box. The other side of the channel doesn’t have the cut out half circle area.
Put one tab in the channel that doesn’t have the half circle cut out. Then put the other tab where the cut out circle is and lightly pull or pry the tab into the channel. The half circle area allows you to only have to pry a little bit to get the tab into channel. And a new lid is stronger and more flexible than your old lid.
You will get the tab in the channel and won’t break the tab if you pry and pull where the half circle cut out is.