Hello,
For the e-ticket generation, I suppose that you're using HikaSerial (thus the HikaSerial forum will be more appropriate).
The "Attach serial" and "Pdf serial" plugin allow to send the ticket with the email confirmation or via the HikaShop product file link.
While the admin can download the file via the order details ; the customer can too.
There is no feature to only allow the admin to download the ticket since the base of the component is to automate the generation.
But, if your feature request can also be useful for other HikaSerial users ; we can see to add it in our TODO list.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.