How to upload user files without publicly showing

Hi to all,

We are currently using Ninja forms for our users to submit some applications for our website. We use the Google drive plug in for storing the files these user submit to our local company storage space. For some time now, the Google drive upload setting is not working, Google is slowly disabling their services with plugins like these.

So we need a way without using a similar plug in like ninja forms for our users to submit their applications without these being publicly available. (in the past, and before using ninja forms, we had an issue with forms being submitted and stored in the WP storage but the applications were vulnerable for being accessible online. WE DO NOT WANT THAT)

Thank you in advance.

The page I need help with: [log in to see the link]