I will expand on Holzohr’s good advise;
MinimServer is hopefully already on your Synology NAS, all you should have to do is enable it and update to current firmware via MinimWatch.
You will have to install MinimWatch on your PC or Mac, it will give you a point of control for MinimServer, instructions are very easy to follow on the MinimServer website.
BubbleUPnPServer will need to be installed and enabled on your Synology NAS ( if it is not already ) just google it and you will find the instructions on how to install it on the Synology NAS.
If you are going to use an Android device as a means of control, you will have to have a BubbleUPnP app installed on it. I recommend buying the licensed versions vs the free versions.
If you are using an iOS device, Linn Kazoo / Kinsky and Lumin are nice control apps.
I will not comment on the possibility of Roon.
If you are not too tech savvy you are in for a learning curve, do not worry, there are a lot of great people in the forums that are more than willing to lend a hand to help you work through the process.
Patience, perseverance, a few shots of whiskey and you will be in audio nirvana!