Unable to make purchases with 6€ balance in Apple ID

A possible reason for seeing this message is Apple cannot find a functioning payment method such as a credit or debit card to use in association with making this purchase. You may not have adequate balance. Even free apps may require the presence of a payment method, although it won't be charged if they are free. They may also require a payment method such as a card be present even if you have sufficient balance in your account to pay for an item.

Use the document Add a payment method to your Apple Account - Apple Support to review your payment methods such as credit or debit cards. Problem methods will usually have a notice in red lettering below them. The article: If your payment method is declined in the App Store or iTunes Store - Apple Support has some information about declined payment methods.

For information about updating payment methods on various platforms (iPhone, Mac, etc.), click here --> If you need to change or update your Apple Account payment method - Apple Support

If there's an issue [such as you having a subscription or being a Family Sharing Organizer], add a new card first, then remove the old card.

If using Apple Account balance to pay for an item, ensure there is adequate balance to pay for the item, including tax if applicable. Read this article about how to check your Apple Account balance.--> Check your Apple Account balance - Apple Support Some purchases may require the presence of another payment method such as a credit card even if the final payment will be made by account balance.

If the information above does not deal with the problem then you may find the fastest route to resolution would be to accept the invitation to contact Apple for assistance with this. Ironically there is no “iTunes Store Support” in Apple’s list of support options. I suggest you instead contact billing support. Do this:

1. Click on this link --> https://getsupport.apple.com/?PGF=PGF63006&category_id=SC0060&symptom_id=23372

2. Scroll down to the bottom.

3. Select a chat session or a phone call.

If that fails to work, this support article has various country telephone numbers for contacting Apple for support and service ➔ Contact Apple Support - Apple Support

Any ongoing subscriptions?

Did you already have a look at the general troubleshooting mentioned in this article?

If your payment method is declined in the App Store or iTunes Store - Apple Support