First of all, make sure that you have not received several activation emails: if an activation link has not been opened within 24 hours, a new link is generated.
If this is not the case, and you clicked on the activation link you just received, then it is possible that your account is activated even if the website says "Invalid or expired activation link". This usually happens if you open the activation link with a different browser than the one you used to create your account.
If this happens, wait for a couple of minute: if you receive an email that confirms your account is activated, then you can safely log in with your credentials with Genymotion Desktop.
Note
When this happens, you are not redirected to the page where you can select Genymotion free trial. If you wanted to get Genymotion Desktop pro trial, do not hesitate to use this form to request a trial license from us.