Hi Jose.
My properties are currently with PM's, but all of our properties are D class so I might be able to provide some insight.
With D class, a lot of people don't have credit or even bank accounts, and anything on-line that they can't easily do on their phone isn't going to work. We still ran credit, to check for evictions and to see address history. We would pay for the screening. It is a minor expense to get more completed applications to choose from.
Is it just you?
My husband and I would divide and conquer. He would chase leads, show the units, and try to get completed applications turned in. Ours were not electronic, they would fill them out at the property if they were interested, or drop them by later. Not everyone was and that is normal. We tried to do the showings open house style, "I'll be there 10-noon today and 2-4pm tomorrow, stop by."
Once we got a completed application, it would go to me and I would process them in order as fast as I can. Once we offer the unit to someone we let all other applicants know it is rented, even the ones that didn't qualify.
Using checklists and staying organized is key to staying on top of things and not having any discrimination issues. Find a centralized place to keep track of information you know about interested parties and can make sure you are moving them forward through the process.
Good luck!