Orca Software uses a secure web connection (https) for its websites that require a login. This is done to avoid that passwords and other possibly sensitive data is transmitted over the public internet in plain text.
An important part of a secure web connection is establishing whether the server you're connecting to is indeed the server you're expecting to connect to. This is done by means of a certificate. Upon connection, the server presents this certificate for your computer to verify. Your browser and/or OS does this verification by checking whether the certificate was issued by a valid certificate authority. Getting a certificate from a certificate authority is quite expensive, so the certificates used on Orca Software websites are so called "self signed" certificates and you'll have to install the Orca Software CA as a party you trust in order to avoid your browser complaining about them.
Install the Orca Software CA by downloading the certificate file and installing it in the "Trusted Root Certificates" store (On Windows: select "Place all certicates in the following store" and explicitly select this store) or by running the following installer that will install the certificate for you (Works for Windows + IE or Chrome, FireFox has its own certificate store, so you'll have to use the certificate file).