Please add the actual animations to the project. This only includes the library and that library is based on A-Pose without Fix Silhouette enabled. It is not able to be used by any T-Pose models. If you include the FBX or GLB, then I can fix it myself to work with my T-Pose based models.
Viewing post in Godot 4 Third Person Ladder Project comments
If you want to use the existing animation with your own model, you can import the model(A-pose) and retarget the skeleton. Then, just add the animation library(check Animlib folder) into animationplayer. If you have any problem in retargeting animation in godot, i suggest to check the godot documentation first.