Hi AiioApeira ,
Thanks for your question.
Our default templates try to cover as many cases as possible. These cases include linking to BOM materials.
As you are using a template with linked BOMs set and you don't include BOM data, the import process fails.
If you copy the default template to a new custom one (or just create a new one from the scratch) and remove all linked BOM related data, the import process should work as expected.
You can find how to create a template from the scratch or just by duplicating an existing one here.
Hope this helps,