You can fin the code for you League of Legends match in different ways.
Once the match is ready, the code si automatically sent to your sign-up mail, along with the link for the match
You can find the code in your match page
How to find my match page?
You can either go to your notifications and click on the latest notification about your match, click on it and you'll be on your match page.
Or you can followe these steps:
Step 1: Once you're in the homepage, click on the tournament you are playing
Step 2: You're now on the tournament page, click on the "Brackets" link, right under the tournament name
Step 3: Done!
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