All of the tickets in your order are sent to you in a single PDF, with each ticket on its own page. Because each page admits one person, every ticket will automatically show "admits one."
If you've ordered multiple tickets and can only see one, try scrolling down through the PDF as the others will be on the pages that follow.
My ticket is for a group — is that normal?
In some cases event organisers offer group entry deals as a single ticket. If this is the case, the ticket name will usually make it clear how many people it covers, so check the ticket name first before getting in touch.