The meaning is the same (have to), but the construction is different:
"je devrai faire un choix" is the future of "je dois faire un choix" = I must make my choice
"il me faudra faire un choix" is an impersonal formula (il faut, il fallait, il faudra...) that you need to complement with indirect object "me" (= to me) to make it clear the choice will be yours.
-"il faudra faire un choix" does not tell who will have to make that choice.
You don't have a private teacher checking on your translations, but a computer comparing what you wrote with the correct translations listed in the database. If you miss a word, your sentence is rejected; if you change the word order with no grammatical reason, your sentence is rejected.
Il belongs there, because it's part of the phrase "il faut", "it's necessary" (or in this case, because it's future, "il faudra"). The "me" in the middle makes it a bit tricky. Il me faut means "it's necessary for me" to do something. Or... I have to.
The "un" is because it's un choix. "A" choice. Otherwise it would be something like "I have to make choice."
Why "Then it will force me to make a choice" is not accepted?
I know the best possible translation might be what is suggested by Duo, and "il faudra" is the future tone of "il faut", and! "it is necessary for sb to do sth" is the relevant translation, but my sentence should be accepted as one possible translation.