@Liina wrote:
... I have to verify my email address at first, but this is impossible. Is there a chance to change the email address ...
You can try contacting Support, but without access to the email account you may not be able to gain access to the Dropbox account. You need to maintain an active email address on your account so you can receive verification emails, password resets and one-time security codes used during sign in.
To contact Support, visit the Support page while you're NOT signed in to a Dropbox account, including these forums, and you'll see an option for sign in issues. It's best to use an Incognito or Private browsing session to make sure you're not signed in.