Unable to map existing skeleton

[amk720]

I'm trying to rig a model but it throws an "Unable to map existing skeleton" error. I've tried looking for numerous solutions online but to no avail. Some of the answers I've found point to the fact that my model has multiple floating meshes. Is there a way to solve this issue without having to visibly join these parts?

Here's a link to the model:

https://drive.google.com/drive/folders/1sX5hRQS1YgA2WrElY6nfZHAdhXTwUPQH?usp=sharing

I can upload more files to the folder as needed.

[Ussnorway]

you have to repair the model, so floating bits and missing parts need to be fixed + its actually a glb not Obj