You can use a cloud-based service to upload your files and then create a link on your site for your readers to easily download the file.
Google Drive and Dropbox are two popular FREE services.
Check here for more support on the topic: https://files-en.simdif.com
How to sell file downloads (for Pro Sites)
SimDif offers several ways to sell digital downloads such as music, e-books, videos, and other files, in the E-commerce solutions available to Pro sites.
Go to 'Site Settings' > 'E-Commerce' > 'E-Commerce Solutions'.
Both Ecwid and Sellfy stores support the sale of downloadable files.
The Gumroad and Sellfy options in Digital Downloads allow you to sell file downloads using "Buy Now" buttons.