You need to create SharePoint sites beforehand. Here is an article about migrating Google workspace to Microsoft 365: Switch from Google Workspace - Overview, you can take a reference to it step by step. In step8: Migrate Google files to Microsoft 365 for business, as described in the article:
14.In this case, we have added a SharePoint site called Migrated files, and taken note of the URL for the documents page.
15.We then created a CSV file using the format of Source Path, Destination Path, and Tags.
It indicates you have to create SharePoint Sites in advance, and use a CSV file to map source Path and destination Path.
If an Answer is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.