Digital delivery in RapidCart Pro requires Amazon S3.
We have a long experience now (thanks to RapidLink) when it comes to combining self-hosted digital delivery and the average - cheap - hosting service. This combination often leads to troubles.
Amazon S3 is incredibly affordable but still offers better performances and security when compared to the majority of hosting services out there.
Some users start complaining without even having a look at Amazon costs, which is free for the first 12 months and then is charged few cents per GB. More info at Amazon S3 Simple Storage Service Pricing - Amazon Web Services
This is why we’re not planning to add self-hosted digital delivery support in RapidCart Pro at the moment.
Did you had a look at the new Paddle stack by @instacks?