1. (ACF = Advanced Custom Fields Plugin)

You can use ACF and create a download field on your post template and then code a button on the actual template to read the ACF custom field.

2. Custom PHP Code
You can create your own custom fields in your theme or write a plugin if you are familiar with PHP to accomplish the very same thing you could do with ACF above. usually people find using a plugin much easier than writing code when starting out.

3. You could get past the “more complicated fussing around” part of the Easy Media Download Plugin since you are already somewhat familiar with it.

4. You could hire a developer to do the work for you

Remember, the only reason why it is complex to you is that this is all new to you. I am sure you didn’t ride a bike the first time you jumped on one. Have confidence and faith and ability to learn and fail a few times, there is no penalty for failure if you are learning from it.

I would suggest you take a complete backup of your site before you start anything so you can easily roll back to a good version of your website if you totally screw everything up – which by the way we have all done more than once.

Good luck in your pursuit.