You have to click the link on the SCAP website Starbucks has. It will take you to an application that is for partners only. It will be available to you for free. I did this last night and was confused as well.
$1 if you scroll down, it says “Apply today!” As a link. Click it. It will ask you if you’re a Starbucks employee and your partner number. If you’re having more trouble, let me know!