What is the purpose of these Unix groups?
com.apple.sharepoint.group.1
com.apple.sharepoint.group.2

Directory Services.  These groups for for the permissions of sharepoints (not to be confused with Microsoft SharePoint); shared folders, volumes, drives, etc.

com.apple.access_ftp

FTP file sharing.  This defines the access rights/permissions for FTP (File Transfer Protocol).  It a long since deprecated protocol/service and you should be using scp instead.

com.apple.access_screensharing

Remote Screen Sharing.  This defines the access rights/permissions for screen sharing (or &quot;remote control&quot;)