Driver side axle

It is very likely that this has been discussed in the past, but I didn't have luck finding anything. In the final stages of an engine replacement in my old Mazda 3 (2006). I got a 2.3 Mazda engine from LKQ very reasonably priced. The thing is in; my current step is the axle installation. I'm having a ton of difficulties making the driver side shaft go in. Without the clip it goes all the way in. I've tried with the clip opening upwards, as it says in the workshop manual, and downwards, as it says in the Haynes book. Both options aren't working.
My hope is that someone here knows a trick to make this work. The wheel assembly is to the side, not in the way.
Please, help! Thanks.