What grammar structure does ...在这份评估单上打分... use?
How is  在 + 这 + 份 + 评估 + 单 + 上 + 打分 translated as : "fill the test report" / "rate this evaluation form" ?


"在 ~ 上"  is  a preposition: (on top/ on above)


  [在 (object) 上] = [on top of (object)]


The object here is "这(this) 份(classifier) 评估(adjectival phrase) 单(noun)" = "This assessment form"


  Now we know the 'object' in [在 (object) 上] is 'This assessment form', we get: [在 (这份评估单) 上]


Since we have the object, now we need a verb to make it a complete sentence. And "打分" (give marks) is the verb in this sentence.

"[在 (这份评估单) 上] [打分]" = "[preposition] + (object) + [verb]" = " on this assessment form give mark"

You can place the verb before the noun and the sentence still make sense

"[打分] [在 (这份评估单) 上]" = "[verb]+[preposition]+ (object)" = "give marks on this assessment form"

However, "在这份评估单上打分"(object before verb) emphasize the object, therefore it is preferred over "打分在这份评估单上" (verb before object), which emphasize the verb. 

In this context, the writer wants to emphasize the object because it is more important that you know where to apply your action (evaluation) than what to do with the object

份 as a classifier means "a portion of'; 'a set of';  which can apply to 评估单, as in "一份评估单" ---> "a (set of) assessment form" 

We don't actually need a classifier for "form" if we are not counting or indicating the number of it. You can omit the classifier and write "在这评估单上打分" or even "在评估单上打分" here