The normal meaning of kredit is a loan, so the answer should be “We need a loan from a bank”.
The sentence makes more sense in English as "We need credit from a bank." You can use "a credit" in English but it means a single line in an accounting tally.
Your version is most likely what they intended to write ; however 'a credit' can also mean a refund and is a common term when referring to a fee cancellation. Best to report suggestions so that the app improves.