Translation:

I downloaded the free 30-day version of Vegas Pro 22 from the official website, but it says "serial number." What should I do?

Please see if this quote from a FAQ (item 39) helps: "When you first run VEGAS Pro after installing, click "Start trial version", then click "Register now". A page in your default browser should open where you will be prompted to make a MAGIX account, if you do not already have one. If that page does not open, check your default browser setting, or try launching your browser before clicking "Register now". A trial registration code should be emailed to the address you provide. Check your spam folder if you do not receive it. If you still don't receive it, try clicking "Register now" again to repeat the process. When you receive the code, enter it on the VEGAS Pro welcome screen then click "Test program". Your trial is valid for 30 days. If you later decide to purchase it, you can activate it fully without reinstalling."