I have Minecraft installed, I have a Microsoft account attached to it from when Microsoft migrated Mojang accounts to Microsoft accounts, yet I'm getting the "you haven't purchased Minecraft Java Edition" error

[TheJacobSurgenor]

I literally don't know what to do

[a0085913]

I ran into the same problem. Like @JaariAtmc sais: You have to log in to minecraft.net, go to "My Games" and look for the tile that sais "Minecraft: Java Edition". Here, click on the "Profile Name" option and set your name. After that, close the launcher (if it isn't already closed) and delete the oauth-folder under "%appdata%\.technic". Relaunch and then it worked for us just fine  Hope this helps  

[JaariAtmc]

You still have to set your username that's associated with your minecraft/microsoft account combination.