Accidental purchase of a photo with a "Plus" license

You can try to explain your misshapen by contacting Adobe customer service. Normally you get asked for a confirmation as soon as you licence something that costs more than 1 (one) credit. The plus licence is the German expression for the enhanced licence. So I suppose you licensed a Premium asset.

If you have a Teams account, you need to contact a plan administrator for negotiating with Adobe Customer care via the admin console.

If you have an individual plan, you can contact customer service directly. Adobe customer care can be contacted by beginning a secure chat session at https://helpx.adobe.com/contact.html?rghtup=autoOpen. Pop-up blockers need to be disabled, you need to accept cookies! If the chat window fails to open, or is non-responsive, use a different device and/or browser to start the interaction.

For support via Twitter:
https://twitter.com/AdobeCare

(see also here: https://community.adobe.com/t5/creative-cloud-services/how-to-contact-adobe-support/td-p/11875703 or here
https://community.adobe.com/t5/account-payment-plan/how-to-contact-adobe-support/td-p/11843852)

Important: Adobe does NOT contact you unsolicited by e-mail or direct message. If you get contacted by direct message from a person, claiming to be an Adobe employee, look at that profile and check if they bear the “Adobe Employee” marking under their name. Adobe support does not use Skype to give you support.
If in doubt, ask the forum.