"Please put the painting here."
I think DL wants us to use the 吧 structure which requires the object come before the verb. If we were to put 画 at the end, then that would create a standard subject-verb-object structure sentence which does not require 吧。 In theory something like 请在这里放画 may work but again I think DL is looking for 吧 structure。 However， 请在这里把放画 would be grammatically incorrect because the吧 structure requires the object come before the verb.
I believe the 吧 structure usage is intended to place emphasis on other parts of the sentence besides the object, and to address the rule that you can't put an object right after a verb, and then put other modifiers of the verb after the object. So, in this example, using the 吧 emphasizes the location这里, and not the object 画。 Hope that helps.