If you are selling in the German market then LUCID registration number is necessary for the approval of the listing. As you are saying that you have listed the product 2 months ago at that time amazon allowed you to list the product and you have started selling the product but now if amazon requires it then you have to submit the LUCID number because without LUCID registration number you cannot sell the items in German market.
No, you cannot sell a product in the German market without a required LUCID number, which is necessary for tracking and disposing of certain products in an environmentally friendly way. Update your listing with the LUCID number to avoid legal consequences. Contact relevant authorities or a recycling company to obtain the number.