Go to your crosshair settings and click on the import button (if you can't find it, look at the image below). Paste your crosshair code there. You now have your new crosshair ingame.
Valorant has a limitation of 15 crosshair profiles. When you reach this limit, you need to delete one crosshair before you can import another one.
Valorant's crosshair preview is a bit buggy. Just try it out in The Range, the crosshair does look like the preview on the website.
No. Importing crosshairs is a feature added to the game in patch 4.05. We are just a collection of crosshair codes (literally just text). There are no downloads or programs to run.
We want to keep the quality of our database somewhat high. To avoid people spamming trash crosshairs, there is a cooldown for adding crosshairs.