There are various SEO advantages to sharing PDF, documents & PPT/PowerPoint presentations.

The benefits of PDF submission service are summarized & detailed below:

Organic traffic will increase
Your website will be reliable in search engines
High Authority Backlinks :

High authority backlinks to your website can be generated by submitting PDF, PPT & documents to various sites. Backlinks are essential for SEO because they tell search engines that your website is authentic & trustworthy. It is also a link building strategy.

Search engine reliability/Brand Value:

You may position your brand as an authority in your niche by regularly posting informative, high-quality content. Your SEO efforts may benefit from increased user & search engine trust as a result.

Enhanced Visibility:

Content that is shared across several platforms is more visible. Your documents are more likely to show up in search results when people search for similar topics on Google, Bing which will increase organic traffic to your website

Here some Site List:

Google Drive(DA-97)
Dropbox(DA-95)
4shared(DA-93)
And more..
Note: I do not work with alcohol, gambling, casinos, porn, etc website.