I've received this kind of offer before. eBay can be a little tardy in sending you the voucher code, so once you qualify don't be afraid to jump onto chat and demand it ;) If you haven't received an email you can still check in eBay under promo offers, or just try accepting the promotion via the link given.
- Receive a $20 eBay voucher when you list and sell tech items totalling to $200 or more on eBay.com.au during the Promotion Period.
- Receive a $30 eBay voucher when you list and sell tech items totalling to $300 or more on eBay.com.au during the Promotion Period.
- Receive a $50 eBay voucher when you list and sell tech items totalling to $500 or more on eBay.com.au during the Promotion Period.
- The promotion runs from 00:00 (AEDT) on 11 October 2018 to 23:59 (AEDT) on 1 November 2018 (“Promotion Period”).
Limit of 1 voucher per person.
T&Cs mention this is for selling tech items - I queries eBay as to which categories that applied to and was given this link - it's obviously been created for some other purpose but at least defines tech.
Note there are some excluded selling categories (cars, boats etc) and other conditions in the fine print, so have a quick read through those before mentally spending your voucher.
Might want to fix that :)