Interesting (older) comment that I also have today (June 15, 2021). I see despite a link to 'Magix Customer Service', you didn't get an answer to your question for almost two years now.
I have had Samp Pro X 365 since the beginning of Ver 5. No auto updating to Ver 6 showing up so wondering if despite perpetual service subscription, you have to pony up more money each Version? I pay about $25/CDN monthly just for the program. I see an update offer to pay almost $50/CDN for Ver 6. At that point, I go elsewhere despite my liking of the program i.e. I'm an amateur musician and that is getting pretty pricey for a subscription.
Here is what was posted on the dedicated Samplitude Forum by a user:
You must go to your account and download the new installer for Ver 6 and install. You are also obliged then to uninstall Ver 5 from your system and it isn't an 'upgrade' over top of Ver 5.