Hi Youki,
We are little unclear with the update.
We suspect that you are trying to install both Syncfusion Essential Studio and Syncfusion Studio for Windows Forms in 18.3.0.35. Kindly provide more clear details about which build you are installing and in which order you are trying to install them and the problem you are facing in it (with image illustration if possible). It will be more helpful for us to understand the exact scenario and to provide a prompt solution.
Regards,
Mohanram A.