Hello,
There are some reasons that may cause the referral link "does not work" when used to register, most of them are because of invalid URL format, the referrer account is not active, the referrer does not eligible for new referrals, and/or the referral link is not used during registration.
To allocate the issue, we need to know your referral link and also your site settings.
If you do not want the administrator to be a referrer, you can use random referrer and/or visitor referrer options (Admin CP => General Settings page).

Regards,
By the way, are you sure using v1.3? if so, you are using outdated version. The latest version is available to download for free by an active license.