Specific tax rate based customer group and geo location

Hello,
I'm new to opencart and this is my first project, so I'm very confused about setting up some things. I have opencart 3.0.3.2
I will try to explain my problem. First of all, I don't know if my approach to the problem is right but I couldn't find any solution.

What I want to set up:
• When a customer belongs in a specific customer group (e.g. Invoice group) and he is in EU then I want to have zero tax rate
• When a customer belongs in another customer group (e.g. receipt group) and he is in EU then I want to have tax rate of his country

What I have done:
• I have created two customer groups (Invoice and receipt)
• I have created also one Geo Zone that contains all EU countries, and some other Geo Zones for some EU countries e.g. one Geo Zone only for Greece, one Geo Zone only for Germany etc.
• Then I created Tax Rates for each EU countries with their taxes
• At Tax Classes I created a class that contains the EU tax rates from the previous step

Then what ? What I must do to associate the customer group with Geo Zone in order to display the correct VAT ??

Any answer will help.
Thanks in advance.

I don't think you can associate Customer Groups with Geo Zones, I think their Geo Zone comes from their shipping address.

Hello, thank you for your answer.

So how can I accomplish that ? Is there any workaround?