To answer your question, I would say you need +100 keys to achieve the economies of scale and feasibility to hire a property management company.  

These platforms pool funds from multiple investors to invest in a diversified portfolio of real estate projects.Real Estate Investment Trusts (REITs):REITs are companies that own, operate, or finance income-producing real estate across various sectors.

To answer your question, I am not familiar with that DIY company but know of another one that a peer uses that might be lower for a property of your type.  

For example a lot of property management companies want the owner to indemnify the property manager even if they were at fault / potential did something illegal.

Company is Wholesaling PPC, we might be a good fit for you.

There are also large tech companies moving in like Amazon. 

However company match is 50% max at 6%.

Direct with seller (Through their own marketing)  they typically have more control of the seller and also more often have a reputable title company the usually work with . ..   

Does anyone have any recommendations on reputable companies and/or a reference?

And then find a quality PM company, and get their guidance on rental market and trends.