When the date came he said he wasn't going to submit it by the online app (stipulated in the lease) but would have it in cash and that we could come pick it up (we live 3 hours away). 

Look at other rentals in the area and see not only how they are advertising or promoting online but also the inside and outside of the rental so you can create a similar environment to try to replicate the same results.

I have looked around online, but haven't had any luck yet, i have local real estate agent there, but they are not expertised on those distressed properties.  

I mainly want a site that offers advertising the property, online payment options, maintenance requests & at least a basic accounting aspect.Thank you in advance!

is there a way for me to create an online STR guestbook for free? 

If you know of any online forums or organizations where I can learn from others and expand my network and knowledge on wholesaling or getting my first deal, I’d really appreciate any recommendations Thanks in advance for your help!

He has no social media, no pictures, no videos, no online presence, nothing.

If you want to put the deposit in a out of state/online bank, then you will have to furnish a bond.  

In Land Investing Online there is a free support group as well as an affordable monthly subscription (I think $100) where you can share your deals for input from the other members. 

You can also check their reviews online at Google, Facebook, or Yelp.