If you used the Lr 6 trial (or CC equivalent) to make that catalog, the message means exactly what it says. It can't be opened by version 5.7.
It seems you have used the catalog in Lightroom 6.
Lightroom 6 catalog cannot be opened in Lightroom 5.
You may go ahead and create a new catalog in Lightroom 5 or use any catalog created in Lightroom 5.
Hope this helps.
Thanks everyone! I will attempt to just create a new one. If I can get the program to open.