A group of Microsoft Products and technologies used for sharing and managing content, knowledge, and applications.
Hi Harold,
A distribution group can’t be synced to SharePoint Online, you can’t give site permissions to the members in the distribution group.
To meet your requirement, I suggest you use an Office 365 group instead of a mail-enabled security group and a distribution group. When an Office 365 group is created, a team site will be created and the group members will have access to the site automatically.
Thanks,
Cliff