Access Transformer Library is missing - trying to load 1.15.2 server on own computer

[ULTIMAMORI]

Hey! I keep getting this error when I start my own Minecraft server:
(Also to note: I am not very knowledge on how Java works as my servers have almost never had any type of issue)

2021-10-23 18:47:36,993 main ERROR Error processing element Queue ([Appenders: null]): CLASS_NOT_FOUND
2021-10-23 18:47:37,041 main WARN Advanced terminal features are not available in this environment
2021-10-23 18:47:37,078 main ERROR Unable to locate appender "ServerGuiConsole" for logger config "root"
←[32m[18:47:37] [main/INFO] [cp.mo.mo.Launcher/MODLAUNCHER]: ModLauncher running: args [--gameDir, ., --launchTarget, fmlserver, --fml.forgeVersion, 31.2.50, --fml.mcpVersion, 20200515.085601, --fml.mcVersion, 1.15.2, --fml.forgeGroup, net.minecraftforge, nogui]
←[m←[32m[18:47:37] [main/INFO] [cp.mo.mo.Launcher/MODLAUNCHER]: ModLauncher 5.1.2+70+master.2845bb9 starting: java version 15.0.2 by Oracle Corporation
←[m←[1;31m[18:47:37] [main/FATAL] [ne.mi.fm.lo.FMLLoader/CORE]: Access Transformer library is missing, we need this to run
←[m←[1;31m[18:47:37] [main/ERROR] [cp.mo.mo.TransformationServiceDecorator/MODLAUNCHER]: Service failed to load fml
cpw.mods.modlauncher.api.IncompatibleEnvironmentException: Missing AccessTransformer, cannot run
        at net.minecraftforge.fml.loading.FMLLoader.lambda$onInitialLoad$1(FMLLoader.java:104) ~[forge2.jar:31.2] {}
        at java.util.Optional.orElseThrow(Optional.java:401) ~[?:?] {}
        at net.minecraftforge.fml.loading.FMLLoader.onInitialLoad(FMLLoader.java:102) ~[forge2.jar:31.2] {}
        at net.minecraftforge.fml.loading.FMLServiceProvider.onLoad(FMLServiceProvider.java:122) ~[forge2.jar:31.2] {}
        at cpw.mods.modlauncher.TransformationServiceDecorator.onLoad(TransformationServiceDecorator.java:53) ~[modlauncher-5.1.2.jar:?] {}
        at cpw.mods.modlauncher.TransformationServicesHandler.lambda$loadTransformationServices$11(TransformationServicesHandler.java:131) ~[modlauncher-5.1.2.jar:?] {}
        at java.util.HashMap$Values.forEach(HashMap.java:1067) [?:?] {}
        at cpw.mods.modlauncher.TransformationServicesHandler.loadTransformationServices(TransformationServicesHandler.java:131) [modlauncher-5.1.2.jar:?] {}
        at cpw.mods.modlauncher.TransformationServicesHandler.initializeTransformationServices(TransformationServicesHandler.java:56) [modlauncher-5.1.2.jar:?] {}
        at cpw.mods.modlauncher.Launcher.run(Launcher.java:75) [modlauncher-5.1.2.jar:?] {}
        at cpw.mods.modlauncher.Launcher.main(Launcher.java:65) [modlauncher-5.1.2.jar:?] {}
        at net.minecraftforge.server.ServerMain$Runner.runLauncher(ServerMain.java:63) [forge2.jar:?] {}
        at net.minecraftforge.server.ServerMain$Runner.access$100(ServerMain.java:60) [forge2.jar:?] {}
        at net.minecraftforge.server.ServerMain.main(ServerMain.java:57) [forge2.jar:?] {}
←[m←[1;31m[18:47:37] [main/ERROR] [cp.mo.mo.TransformationServicesHandler/MODLAUNCHER]: Found 1 services that failed to load : [fml]
←[m←[32m[18:47:37] [main/INFO] [STDERR/]: [net.minecraftforge.server.ServerMain$Runner:runLauncher:65]: The server is missing critical libraries and cannot load. Please run the installer to correct this
←[m