After subscribing to the PRO version, you can get the Download ID from our site. Go to k2store.org and then login. Go to My Account and My Downloads. You can see the download ID. Copy and paste it here.
Choose the minimum stability level of releases to be notified for. By default this is set to Stable and is the recommended setting for live sites. If you want to help us build better software with less bugs please consider installing alphas, betas on your test/staging site or RCs on your live site. Your feedback helps us improve the software. Thank you in advance!