They have a space port at 60'N Latitude? Isn't that extremely sub optimal for launching anything to orbit?
Lot of sats are for example spying sats, and these can use polar orbits (as the earth rotates under the sat, sat will at some point map the whole earth), or more fancy orbits that you can read about in this guide here: http://www.braeunig.us/space/orbmech.htm#types
⇒ they’re aiming for the part of the market where that doesn’t matter.
I honestly don't know why the Germans are trying to turn an old Chain Home radar station in the Shetlands into an orbital rocket launch site. For sun-sync polar orbits, it doesn't really matter what latitude you launch from, you aren't getting any benefit anyway, but I wonder at exactly how many of these sun-sync earth observing satellites are going to be launched by the ESA or Europeans in general. This doesn't seem like a particularly large market to me.
For SSO there's a small preference for higher latitudes, because there's less (unwanted) eastward velocity to cancel out.
Well, they aren't. RFA is just one of many customers, which also include British and US companies. SaxaVord spaceport is operated by a Scottish company and there's no connection to anything German other than some customers being German companies. Lockheed Martin UK and Californian ABL Space Systems are operating from there as well.
The ground area is 5200 square km with 6600 square km of closed airspace.