What code do you have so far? Godot will not know what animation to play, you might be able to mark one of the animations as Autoplay or add a AnimationTree to a new Inherited scene to control the animations with less code.
You’ve certainly found the deep end, if you just want to check out the animation right click your glb file and select “new inherited scene” this make a scene of it that can be added to, and messed with. You can select the AnimationPlayer and play animations from the bottom panel to preview them, the Autoplay button will automatically play one animation when the game loads.
@gertkeno I tried this and while it works, it seems that I could not set the looping from there. It will say “Can’t change loop mode on animation embedded in another scene”.
Still though, I got what I wanted from the one line provided @mr.skeletonhater
You can set the animation’s loop mode in it’s advanced importer. Double click the glb file from Godot’s filesystem to change animation settings like looping.