Can't access weekplan since I paid (just says "unauthorized")

I just decided to buy a paid upgrade to WeekPlan. It let me pay and then unfortunately it will no longer let me login from my Safari browser on my MacBook. It says "Unauthorized: You need to log in and try again". I've tried refreshing. I've tried starting a new tab and clicking through from weekplan.net again. I just keep getting this message. I can access it just fine from my iPhone.