Translation:I forbid you to buy anything else on the internet.
Native English speaker here: "I forbid you to buy" doesn't sound proper to me. For me the more proper way of expressing this would be "I forbid you from buying" Forbid for me is always "forbid from [gerund]"; "forbid to [infinitive]" sounds unnatural to me.
"from [gerund]" is how I answered, it was marked wrong, I reported it. Just reporting how I feel about this question.