Forgot to cancel deutsche bahn subscription, getting emails about paying for the unpaid month

I was in Germany last month and bought a deutsche bahn ticket for 60 euros (What a deal!). Unfortunately I forgot to cancel before the next month was charged.

However, the card I had on file (a prepaid mastercard) doesn't have the sufficient funds to pay for it, and so the payment keeps declining. I figured I might be able to get away not paying for a month I didn't use since the card doesn't have the funds.

I've received an email from "DB Vertrieb GmbH" about paying the outstanding fee. In the email, it says:

"If we do not receive or cannot assign your payment by December 17, 2025, the claim will be handed over to the collection agency we have commissioned. To this end, we will forward your data to the collection agency for processing (storage) .

You can avoid the additional costs incurred as a result by

paying us by the above-mentioned date."

(translated from german, might not be exact)

What does this mean exactly? Is this something I can ignore and cancel the CC I have attached on file? Is it a crime to not pay this? I don't reside in Germany (or the EU), will this prevent me from visiting germany in the future?