If you follow my longer guide tailored for CentOS 8, that is what I use actively for my home business right now, and I have tested that much more thoroughly as well. I am able to send invoices and have them pay through PayPal.
Note too that often your problems might be solved by downloading the latest github clone of invoiceninja and running
git checkout v2
As described in the guide since there are more fixes for invoice sending and payment gateway customer portal stuff in the current git clone.
5.0.13 release is still beta, its all beta, so I can only offer so much help. But the git clone is best I recommend.
https://invoiceninja.github.io/selfhost.html#trouble-shooting
If you read here in official documentation it describe some fixes for stuff you’ve encountered, perhaps you’re getting it from here already? (Looks like your LibX issue was listed here as an issue on “some systems” so it might be something droplet related, so I will add it to the guide now I can confirm what it is.)
Well if not I suggest since you are struggling to review this page, and also the Readme document included in the Invoice Ninja package, and again, try the git clone method instead of the 5.0.13 release. I try to recommend git clone but offer the instruction for 5.0.13 because it is at least “stable”, git clone could be different from day to day but seems to only be better for now.
When running git clone, it is necessary to follow up with the artisan storage:link, every time.