Slightly different meaning: "How do I get... " suggests the job is not yet in hand or even close by. Asking for advice.) "How am I getting ..." implies that a job is closer to hand, but that you have some kind of influence over the outcome. Unless of course, it's asked in a state of despair: As in "How am I (emphasize the I) getting a job as a doctor? ... (implying I am a complete failure...) Language is difficult.. Hope this helps a bit.
It is an incorrect use of English for this Dutch sentence. It is how non-native English speakers speak using literal translations from their own native English.
It is correct that this program marks it wrong.
If you insist on using the form "How am I ... " then you need to change the rest of the sentence.
i.e. Incorrect "How am I getting ..." Correct "How am I going to get ..."
To say "How am I getting a job as a doctor" is actually questioning the fact that you are getting the job, and that you cannot believe it.
e.g. "How am I getting a job as a doctor, i didn't even pass the test"