You just wouldn't. The ISS is the largest thing we've ever built in space previously. It has an internal area about equal to a 747 passenger jet. That's about 4800 sq ft, but the entire structure is about the size of a football field, with the solar panels needed to power it and whatnot - that's 57,800 sq ft total space taken up to get that 4800 sq ft. The average data center currently is around 100,000 sq ft. The ISS took about 1000 hours of space walking and 136 space flights to build. So we need 20 times the ISS to build one average data center, so 20,000 hours (that's a team of 10 people working 12 hour shifts for 166 days) of space walking to build, 2700 space flights, and it would^1^ take up over 1 million square feet of space in the sky.
OH, and that is completely ignoring the fact that ISS orbits earth in 90 minutes. Maintaining data transfer capabilities from that to Earth would be a nightmare and building a structure that big that close to Earth also means it's going to be BRIGHT in the night sky (like, ok, not as bright as a full moon or anything, but 20 times brighter than ISS which is the 3rd brightest thing in our night sky already... This data center would be well ahead and into the number 2 spot, you literally wouldn't be able to miss it).
OH OH, that is also ignoring how incredibly difficult it would be to cool. Cooling components on the ISS is one of the biggest challenges because there is nowhere for the heat to go. So add on hauling several million gallons of water to space every month I guess? I dunno what their plan would even look like for cooling that is such a monumental problem.
AND THAT IS JUST ONE AVERAGE DATA CENTER. The cost would be astronomical. The environmental impact would be devastating. The repercussions would be severe. The benefit would be almost non-existent and very short lived if there even was any.
^1^ - Ok, this is all napkin math based on what it took to build the ISS. Could it be done more efficiently the second time around? Maybe, but we aren't just talking about ISS 2: Electric Boogaloo either, we are talking about a giant 20x structure. Chances are it would be even worse than these estimates - and where the hell is SpaceX going to get the actual physical man-power to do the construction of this thing in orbit??