Dauchnie look through this documentation: https://learn.microsoft.com/en-us/universal-print/hardware/universal-print-oem-app-registration in the first paragraph (screenshot; Register new devices) were it says Redicrect URI (second screenshot). And put SOMETHING in there. Either the stuff you see in the screenshot or whatever you like.
But to the second part of your comment. Printers will NOT automatically deployed like it would be when you use a GPO. Think of Universal Print more like a printserver. Once you shared the printer and specified which groups/end users are allowed, they need to (from their client) actively search for it. They will see a printer pop up with said share name and the cloud symbol right next to it.
You MIGHT be able to use Intune together with Universal print so achieve the same level of automation that you had on prem with print servers and GPOs. But I haven`t looked into that yet. Just came back from PTO and need to investigate a couple of aspects of Universal print.
Even though I really like the concept and it PERFECTLY fits into our small office strategy, it still lacks some important details that might turn out to be a showstopper in the end. But that is nothing Ricoh specific rather than an issue of Universal Print itself that could need some detail improvements.