First download the plugin file zip file, then there are two ways for installing:
1) The best way to install is via the Plugins > Add New Plugins section in the Wordpress Backend.
2) You can also manually bu unzipping plugin file in /wp-content/plugins directory
Once the plugin is installed please activate.
After activating you will see a "Upload files configurator " menu voice under WooCommerce menu.
Clicking on Upload files Configurator menu voice, you can enable files upload for View Order Page.
For every upload you can define some additional options like Upload title, description (HTML code is accepted), file types allowed, file size and option to allow user to delete file.
Furthermore under the "options" menu voice can be configured some other common options to the upload fileds (like progress bar color or pload fileds box position on product page)

In Order detail page, WCUF will add a "File(s) uploaded" box in the left of the page. By this box you will be able to download or delete every
file uploaded by user.

Frontend
An upload field, according to its configuration paramater, will be displayed in :
- Product page
- Checkout page
- Order details page
For product page, is also possible configure where the upload field has to be displayed (after variable dropdowns menus, after product description, etc).
Is also possible specify progress bar color and add additional css class to "Browse" button. To configure these options, go to "Upload fields Configurator" -> "Options" menu voice