I installed PSP earlier today and had a moment of panic when in first came up. I thought what the heck, this only can do a few things. Then I realized by default it loads a simplified workspace for doing photo edits on touchscreens. I found where to switch to the full workspace that has all the familiar toolbars and stuff I recognize. It looks like they've added quite a few more things in the past 20 years! I'll have to do some reading up to take full advantage. Hopefully it works ok even if it is a bit slow on my old budget computer... although that is long overdue for an upgrade too. I'm installing VideoStudio now and man the installs are pretty slow... it took almost half an hour!
When I looked at it again I think the referral code perks are maybe only for people that sign up for one of the subscription plans, so maybe you didn't miss out on anything.