A couple of ways to do this
Personally I would probably do this in 2 flows
I would group the documents together in a SharePoint list then use a recuring flow to send and log
SharePoint list will need a choice field "Status" values of "Uploading documents", Ready for Export" and "Exported"
Not sure how you get your files so I'm speculating a bit but
1st flow
When a file is uploaded get the file
Get everything in the list where we are grouping them
Get the attachments on said item
Count the Number of attachments (initialize a variable at the start of the flow and then for each attachment increment it)
Use a control that if number of attachments is greater than or equal to 10
if less then add it to this item
If 10 Change the status of this list item to ready for export and add a new list item and add attachment to that set the status value as uploading documents
(Note: if you are uploading multiple documents at a time you will need to put this in a for each loop)
2nd flow
Recuring every Friday at whatever time
Get items from the list
inside a for each if status equals Ready for export
Get attachments and put them on an email and send it
Then Create a folder in your document library with your naming convention and add the attachments in there
Finally update the list item to Exported so it doesn't pick it up twice
Alternatively you could add the export Audit data to the SharePoint list in a column this is what I would do but I don't know your auditing requirements so I'll Let you decide on that
If you are storing all these in files you will probably want to have a 3rd flow running to delete any items with a status of Exported to keep the runtime down
