I converted my private account into a business account and still don’t have an eBay Shop. Did I misunderstand that I have a free quota of 250 listings with the listing fee?

Hi @thekthek yes, you misunderstood that. Without a shop subscription there are no free quotas for commercial sellers:

Listing fee for commercial sellers free quota 250 listings | Members help members

Listing fee for commercial sellers free quota 250 listings | Members help members | eBay Germany