I had the disc version for the main game and digital for the DLC and it was kind of a pain considering even the saves don't work until you've installed everything. Glad I was able to grab the complete package.
Just a friendly heads up. The nominal difficulty for the DLC (or expansion, rather - it's quite similar to Blood & Wine in that it's a whole new section of the map, and running an updated version of the engine, the snow deformations are insane but you won't find them outside the DLC area) is 30, but if you're playing on higher difficulties (hell, on normal even), that's way too low. I'd say level 35+ starting out, and you might need to grind it out even more to complete the main story ending. It really ramps up the difficulty.
But you get new weapons more suited for the DLC, some new armor (the "Shield-Weaver" isn't as OP as it is in the base game), some really cool new robots to fight. And also a demo tape of what might have been a hit act, under different circumstances.