I tried to register but I didn't receive the activation email

Firstly, please check your SPAM folder. Some internet servers and email clients may have decided it was SPAM.
You can also try to ask for a new password, which will be re-sent by email.

Note that some emails may take some time to arrive, depending on the servers.
Lastly, if you keep experiencing difficulties, please contact us so we can manually activate your account.

In any case, it is important to check that you can receive our platform emails because payment notifications, deadlines and reward delivery will use that email address.