Downloaded DNG converter for CS 5, can not be opened on macOS Mojave

I recently bought a 7D Mark II without thinking that I can not open raw files with my current system. I've updated from Yosemite to Mojave today to download the DNG converter (which could not be downloaded from Yosemite). Now it seems like the DNG converter has been downloaded, but if I double click on the icon in my downloads, the installation process will continue immediately. In my understanding, I had to download with Mojave 10.2. When this did not work I tried 11.2. The same thing happened with both. Does anyone know what I have to do to make this work without investing in another version of Photoshop? Many Thanks!