Bitrix24 users can not only upload files, download from external Drive or select from Bitrix24 Drive, but also create new files right from the Activity Stream (More > File):
There are several options available:
- create using Google Docs;
- local applications;
- Office 365;
- MS Office Online.
Add recipients to your Activity Stream post in order to share created file with other users (remember you can add external users to the post as well).
You can always find the files created in Activity Stream under Bitrix24.Drive > My Drive > Created files. Use sharing option in the folder options menu to share this folder with your colleagues.