Ares (stylized "ares") is a cross-platform emulator. It also supports many other platforms other than the N64 as well. It focuses first on accuracy of the console it is emulating. This means new cores are slow to get to a point they run a good amount of software, but older cores are fairly solid and do not run into many issues that you wouldn't also encounter on the actual console itself, and it doesn't have any plugin choices.
This also means that system requirements are higher than other emulators for the same platform. There is a chance ares is too resource-intensive to work on your system if you have a lower spec older processor. For N64, ares uses the paraLLEl-RDP plugin behind the scenes so you also need a graphics card capable of Vulkan 1.1. You can check this website to see if your graphics card supports any version of Vulkan. If you're not sure what GPU your computer has, try one of these methods to find out.
Make sure your graphics card drivers are up-to-date.
Install
Official downloads are on the ares download page. This includes a zip file for Intel Windows, ARM Windows, and a macOS universal binary. Just download and extract these somewhere in your User/home directory and they should just work.
Also on the page is a link to the officially supported Arch Linux AUR repository and the officially supported FreeBSD FreshPort. Lastly there is the source code.
While that is the extent of the officially supported binaries, Linux also has the options of the third-party supported Flathub Flatpak or the pkgforge AppImage.
Note that on Linux ares must run on an X server like Xwayland. It does not yet support Wayland due to hard dependencies on X.
Configure
Settings commonly configured before beginning to use ares.
Video
Under the Settings → Video menu the only setting you should look at changing is the 2x Native, and 4x Native settings. These will increase the output resolution of paraLLEl-RDP but will require more processing and video memory. It is recommended to keep this at 1x Native unless you have strong reasons for trying otherwise. If you do upscale, the supersampling option may be desired if the scaling causes the window to grow too large for your screen.
Input
Settings → Input uses a virtual game pad system much like RetroArch does. However, as the UI is not controller-centric, it does not force default controls on you that if broken make the emulator unusable. Under the first dropdown at the top you can choose a specific core to configure like "Nintendo 64". Changing the mappings here will also change the mappings on the virtual pad and therefore affect all of the other cores as well, so be aware of this if you also use ares for other systems.
To configure a mapping, double click under the "Mapping #1" header next to the name of the control you want to map. Then press the button or key you want mapped to that control. "Mapping #2" and "Mapping #3" are intended as ways to bind the same console button to different controller buttons/keys. A common example in Ocarina of Time is binding C-Up and C-Down to the right stick axis in Mapping #1, then in Mapping #2 binding C-Down to the right bumper as well.
Background Input
Under Settings → Drivers, you may want to change the "When focus is lost" setting under Input. "Block Input" is recommended if you will be typing into other applications while ares is running to avoid pressing virtualpad inputs or hotkeys. "Allow Input" will probably work for you if you will only ever be clicking other applications.
Troubleshooting
These are the issues people are known for running into when running ares.
Audio is Choppy / Running at lower than 60 VPS
The very first thing to check if you are having this issue is to turn on fast forward or disable Sync to Audio in Settings → Drivers. If ares is still running below 60 VPS at this point, your processor is not strong enough to handle ares' emulation. Try a different emulator instead.
If your VPS is now above 60 VPS, turn off fast forward or re-enable Sync to Audio in Settings → Drivers. Now that we are certain that hardware isn't the issue, go to Settings → Drivers. Some people have been able to solve this issue by switching the Video Driver from OpenGL to DirectX. Close the Configuration window and ares. Start ares back up and load the ROM and see if the problem is solved.
If changing your Video Driver doesn't change anything, you can attempt to change the Audio Driver. Just try the next one down on the list, close the Configuration window and ares. Start ares back up and load the ROM and see if the problem is solved. If it is not solved at this point you should ask about it on the Discord.