Can someone send me a link for the SimpleAuth PHAR plugin, but compatible with the latest Pocketmine-MP API? I attempted to make it compatible myself but it never worked.
And I wouldn't use the latest API just yet. Most plugins aren't compatible with it yet and when you try to update it by yourself or with pmt something goes wrong. I suggest reverting back to 3.0.0ALPHA-5 build 217 (just because it's the latest of that API version)
The link for that here should do it. Just rename it to Pocketmine-MP.phar when you replace the other Pocketmine-MP.phar with this one. If you need more help I will be here.