I know of only one building that allows Mid-Term Rental 1 month or longer.   

In his experience, Memphis’s higher-than-typical rent-to-price ratio sounded great in theory, but property management turned out to be a huge factor-especially if you’re not local.

It's called PM Build.

Anyone who managed to do this probably did it 5+ years ago when the market was very, very different.If you borrow $200,000 to build an ADU, I suspect you would need to rent it for $5,000 or more to make the numbers work.

How do I acquire the funds to build an ADU to the property?

But keep in mind if your using money you cant afford to get back then buying action property might not be appropriate for your current endeavors and its better to just buy open market were you can do proper due diligence and know you have a build-able site.

It sounds like you’ve got an exciting plan mapped out, and I love that you’re thinking of starting a property management business while building your own portfolio—that’s a smart move.

You need to both build up cash and also a career.2.  

You don't need to know everything to get started; you need a foundation to build on, and the rest will come through experience and then refining your education.You can build a basic understanding of investing in 3-6 months.

Maybe they've been burned by landlords in the past and are being very careful.You can legally reject them based on personality, facial tattoos, body odor, or other factors, but you better make sure you can prove that it wasn't based on any protected class like race, religion, familial status, etc.