Translation:Here is a particularly ambitious plan.
"Here is an especially ambitious plan" was rejected because DL believes there is a distinction between particularly and especially. Could someone please explain that nuance to a 59-year-old native English speaker?
Larousse lists ( specifically, in particular, specially, especially ) as valid translations.
What is interesting, though, is all of their examples use particularly. A small mystery.
"Particularly" is used here as a qualifying adverb → it qualifies the adjective "ambitious", thus it becomes an "adjective phrase".
Adjective phrase fall before a noun and occur after determiners. Hence:
"Here is (verb) a (determiner) particularly ambitious (adjective phrase) plan (noun)".
I, personally, believe your structure should not be accepted.
In english one must say "particularly ambitious plan". "Plan particularly ambitious" is definitely incorrect.