A brief search threw up a few threads I've linked at the end of this post so they may be a good starting point, the care for pairs of any ham species is pretty much the same so they should all help
The basics are fairly simple - a cage of approx 70cm by 40cm floorspare (or slightly more/less depending), two wheels, no shelves, scatter feed the food instead of using a bowl and make sure everything has two entrances and exits
Doing all of that increases the chance of the pair staying together happily.
I think at least one of the threads discourages keeping pairs, I'd like to say now that I love keeping pairs/groups and strongly believe in giving russians and robos the chance to live socially if they're able to have it. Some of our hybrids (the most common "russian" dwarf hamsters) have been amazing in pairs and its been fantastic having them in pairs. Our current pair are great together and quite a few past pairs have been too
First time Robo owner
2male dwarfs in one cage?
Housing for a pair of Campbells?