I can not send documents through email

Make sure iCloud Drive and desktops and documents box is turned as on Use iCloud Drive to store documents on your Mac and iOS devices - Apple Support

Verify that read and write permissions are correctly set up If you need permission to open an item on Mac - Apple Support

Change permissions for files, folders or disks on Mac - Apple Support

with your home folder and the document that is about to be attached in mail compose window Write, send and schedule emails in Mail on Mac - Apple Support

Open finder > icloud section > iCloud Drive > Documents , right click over the personal document and click on copy .

Compose a mail from mail application ( use command and N keys ) , and paste the document in it ( use command and V keys ) , in the " TO " field enter recipients mail address , fill up the subject field and send the mail .

Note : make sure you don't create a large document ( use mail drop ) Add an email attachment in Mail on iCloud.com - Apple Support

Mail Drop limits - Apple Support

With Mail Drop, you can send attachments up to 5 GB in size.