e-tix number is not shown on austrian.com under "My bookings".
When booking via austrian.com, I generally receive a first mail with booking confirmation and the booking reference.
A few hours later a second mail shows up which includes a pdf with the e-tix.

Go and check with your booking reference and name on checkmytrip.com. There you should see the e-tix number. If not, then I would call OS...