Couple things, the requirements listed for this plugin seem incomplete on the Envato page. Troubleshooting my own issues led me to the developers page where the complete requirements are listed and further state:
My site is hosted on SiteGround where I can not change these settings which I suspect are preventing the Custom attachments, which are dynamically generated, to work.
I've had to resort back to the PreBuild option instead. The downside being that it can't be personalized through dynamic tags which reduces half the functionality of the plugin.
The PreBuild option has an issue where it generates a long string of numbers and appends it to the beginning of the file name. This makes the attachment look like junk in the delivered email the customers would never open. It would be much better if you could attach a file uploaded through WordPress's pre-existing Media Upload feature.
I will leave a comment to see if any of this can be fixed or remedied but as is its unusable to me. If any of these issues are corrected I will update my review.
Sorry, As you are facing issue from your server. Please check our reply on your comment about you issue.
Below are reply for your questions
1. For PHP requirement, it’s depends on your file size. If your file size is big then you must have to increase, but if your file size is small then no need to increase. It will work fine with our requirement which we explained in our requirement list on description. But still we will check and update requirement in description.
2. For Naming, We are renaming file because you cant face duplicate issue, if you will upload new file with same name then it wont update with old one, That why we renaming. But we will manage this on our next update.
3. And still you are facing issue in your server then we are here to help you. you can contact at: email@example.com
Then I got your email "My purchase info is below. Just wondering if its possible to remove the large string of numbers and text to the attachments and/or have it select attachments from Wordpress’s normal Media Upload functionality."
So we have updated for you as you want and attached updated plugin on replied email. But still not getting reply from your side. We are still here to help you if you are facing issue. Thank you.
Excelente product, very useful, and the support is incredible.