The problem is that it's very short. The animation is walking. But the animation length is very short and I want to extend the walking.
When I select the walking animation I see it's read only:
After selecting it I can change the time but the clip it self will be still short:
Copy all keyframes, make a new animation clip, drag it out in time...
HOW TO:
You can select every single keyframe by dragging a marquee selection around all those keyframes and copying them.
Then create a new Animation Clip with the "Create New Clip..." choice in that dropdown where it's showing your current clip to be read only.
In the new clip, make sure the timeline is at 0, and past all your keyframes.
Now select all those keyframes again, with the marquee selection again, and grab the handle at the end, it should be a dark blue vertical stripe going from the top of the time line to the bottom. And drag this to the right, as far as you need. This should do an equal time scaling for all keyframes.
To make an animation within an imported model editable, select the model, expand the inner assets, select the animation, then press Ctrl+D (probably Cmd+D on mac?) to duplicate the animation clip. Unity will create a separate copy of it in your assets, which will then be editable.
However, for this specific case, I'd recommend looping the animations (you want the character to reach the door, She simply doesn't go that far in the animation). Otherwise, if you really just want to make the clip "longer", you can adjust the playback speed within Animator. After you add in a clip, select its node and you'll see an adjustable speed in the inspector.
