Hi,
I would like to deposit my AMAX (American Express) credit card und snyc. with the online acc.

It is a card which was issued in the European Union and is denominated in Euro.

Does anyone have documentation for me?
Or rather, do I have to enter a UID among others. Which ID is it exactly?

I use the internal ofx importer, and download data from my US based AMEX card with no problem. I just looked at my settings, and that card does not have a UUID. Is this the first account you have mapped to an online account? If not, the process should be the same as for any other credit card. If it's your first time, you will have to choose whether to use WebConnect of Direct Connect to download transactions. For the former, you do not need to map the account - just go to the bank's web site and download the data as an OFX or Quicken file. For Direct Connect, you can use either the ofximporter or aqbanking. This is mentioned in the Handbook, although not in great detail. I would look there first, and if you have further questions, ask again.