Eastern Arabic digits are read left-to-right, surprisingly. So e.g. in license plates, phone numbers, etc. (where you read the digits separately), you go left-to-right.

When speaking the numbers, you are right, the rules are the same as in German, e.g. Fifty-one is Whahed-wa-Khamseen, so similar to German Ein-und-fünfzig.

P.S: I'm German and live in Saudi, but my knowledge of Arabic is limited, so take it with a pinch of salt.