I'm not getting any option to enter in my wife's profile or income information for some reason - she didn't work this year, but she did have T4E due to mat leave.

Is all she had was a T4E, the easiest way to add it is directly. See this FAQ, but search T4E:

https://turbotax.community.intuit.ca/replies/2648055

When I do this, I get a "Enter T4E Slip for Dylan" (me) - there's no option to add one for her, however.

It sounds like you chose to prepare your return alone and not the option to prepare your returns together at the same time. You'll need to start a new return, so you can answer that you're preparing a return for both of you.
Here's how: https://turbotax.community.intuit.ca/replies/3288128