Plugins for SagerNet is used to provide binaries, which cannot be included in the main application due to their size.
Usage: Install the plugin for the protocol you need
Plugin installed, but it shows "Plugin not found"
The Internet surveillance capitalist monopoly giants in mainland China make a lot of apps (what we call 'tumors') with very poor user experience and many malicious features, including self-launching in the background, waking each other up and pushing ads; when they start producing phones, they ban these things along with the normal apps, but they almost always have some kind of app whitelist.
The standard Android OS does not have permissions named "Autostart" or similar, as this is just a normal cross-application call through one of the four major components of Android, and the plugin does not run continuously in the background.
For this I would recommend flashing to AOSP ROM, or buying an AOSP pre-installed or compatible device.
I'm not using a faulty system, so I can only offer some vague suggestions in the documentation, like granting all relevant permissions.
Failed with "... exits too fast"
This is a generic message without any information, basically due to problems in your profile.