An account isn't required for anything on this site — screenings, Battle and Royale all work exactly the same without one. It exists for one reason: to put you on a leaderboard and remember who you are between visits.
The link in the confirmation email works for 24 hours and can be clicked from any device or browser, signed in or not — the link itself is the credential. If it expires, or you signed up without checking your inbox first, there's a "resend verification email" button on your account page.
From the account page, signed in, you can change your nickname (subject to the same rules as at signup, and to it not already being taken), upload an avatar, and change your password. The avatar is resized and compressed in your browser before it's sent — there's nothing to configure, just pick an image.
Two boards: Cringe Battle wins, and the best Cringe Royale win streak you've ever had. Both always show the top 10. If you're signed in and your own score doesn't put you in that top 10, your actual position is shown separately underneath — you're never left wondering where you stand just because you're not near the top.
A win only counts toward these if you were signed in while you played the game that earned it. Playing anonymously is exactly as functional as always — it just doesn't add to a leaderboard nobody but you would ever check.
Everyone gets one free entry to Cringe Royale a week — signed in or not. If you're signed in it's tied to your account; if you're not, it's tied to this browser, which means clearing your browser's data resets it. That's a real limit and worth knowing rather than assuming otherwise: an account is the only way to make the weekly free game reliably follow you rather than the device.
The week resets Monday 00:00 UTC. Using your free game early in the week doesn't affect anything else — the streak, the leaderboard, and every other purchase all work exactly the same whether that particular entry was free or paid.