Here are some conditions for signups to be counted:
the person you invite should have a different IP address;
the person you invite should have another device;
users being invited need to go through the registration process and use the browser for some time (about 30 minutes) to be counted as an activated user.
If the link doesn't work for some reason, the users you invite should paste your invite link or code here:
To do that, the user should be activated (there is no such field if the user is absolutely new).