Upgrade

I need help, I bought this app and my mac refuses to open it because it’s not the upgraded version of the app. So I went to the app store to upgrade it and after it finished upgrading it still will not open. I even restarted the computer and nothing is happening and it refuses to open. I tried to go to this dudes website and the website cannot be reached. If anyone can help me with this problem I would greatly appreciate it.

Please helppppp about Diary - The most simple and elegant way to keep a journal., v2.0.3