For the DDNet client and for the t-client you will need to execute the following command in the Terminal app after you have installed the client:
xattr -d com.apple.quarantine /Applications/DDNet.app
For the F-Client you will need to execute the same command in the Terminal app after you have installed the client:
xattr -d com.apple.quarantine /Applications/F-Client.app
The macOS Client requires you make it trusted and remove quarantine attributes, because it is an application that was downloaded form the internet and is NOT signed by any official Apple Developer key. If you want to sponsor an Apple Developer account, which costs $ 99 per year, feel free to do so and reach out to me.