Can't update my purchased Taskpaper on OSX

I bought taskpaper for osx in the apple app store at 5 april 2011. Many updates were possible. Now if I want to load the newest version on my new mac mini, the app says the version of taskpaper that is installed, is not campatible with macos monterey. Downlad the newest version on the app store.
On the app store it is not downloadable but only purchaseble. How can I update my taskpaper?

I think easiest would be to download directly from my website: