Hi @Y a h y a ,
1.Would you like to share some information about the brief plan of the structure or how you want to store documents? We have different sites and we can create libraries under them to store files. Just migrate files to different libraries depending on your actual requirements.
2.There are some different types of sites you can choose according to your file needs, team sites may be a good choice. It is more flexible than other sites with special features. You can get more information about the type of sites here:
https://support.microsoft.com/en-us/office/sites-in-sharepoint-545b9394-5641-4576-a10b-e25e5b6eb837?ui=en-US&rs=en-US&ad=US#id0eaabaaa=team_sites
3.Microsoft 365 Groups is a service that works with the Microsoft 365 tools to collaborate with your teammates. In most cases, its functions can meet the needs of users. So Microsoft 365 Groups are more recommended.
Here is an official doc talking about M365 groups in detail:
https://support.microsoft.com/en-us/office/learn-about-microsoft-365-groups-b565caa1-5c40-40ef-9915-60fdb2d97fa2
Best regards,
Elsie Lu
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