That's a 2 level group of quite simple paths. Every path can be accessed separately. You must ungroup the paths if you want to access them with the normal selection tool easily with no errors
If you must divide the paths do it separately or combine those which do not intersect. The big oval and O intersect and shouldn't be combined because it creates a hole.
Here the paths are recolored.
They can be accessed separately in the groups via the Objects panel or with the node tool.
Another possibility is to ungroup twice and then select all + make an union (Path > Union). The result is a single path (= a combined path). That can be easily divided with Path > Division. Here's a result of such attempt: