Normally, Clients work best if the corresponding Server version is the same as the Client version. This is because new features might be introduced in either Client or Server. If version is not the same there might be misunderstandings in the communication between Client and Server. This can result in unwanted settings or behavior.
VisualCron is built to support one version of Client installed on a server. If you install both the Client and the Server it is guaranteed that that version is the same.
If you want to install multiple versions of Client on one machine (to be able to Connect to multiple versions of Server) there is one workaround for that;
1. find the corresponding Client version for download here and download it to the Client computer
2. extract the exe file with tool like 7zip into a folder
3. copy that folder to a location where you would like it to be installed
4. right click on the VisualCronClient.exe file and create a shortcut
5. copy that shortcut to desktop and then we recommend that you rename it with the version number like "VisualCron - Client (8.5.2)" or similar