I get this error when I try and start up my minecraft server:

[23:50:24] [main/INFO]: Environment: authHost='https://authserver.mojang.com', accountsHost='https://api.mojang.com', sessionHost='https://sessionserver.mojang.com', name='PROD'
[23:50:24] [main/FATAL]: Failed to start the minecraft server
java.nio.file.AccessDeniedException: ./world/session.lock
at sun.nio.fs.UnixException.translateToIOException(UnixException.java:84) ~[?:1.8.0_252]
at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:102) ~[?:1.8.0_252]
at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:107) ~[?:1.8.0_252]
at sun.nio.fs.UnixFileSystemProvider.newFileChannel(UnixFileSystemProvider.java:177) ~[?:1.8.0_252]
at java.nio.channels.FileChannel.open(FileChannel.java:287) ~[?:1.8.0_252]
at java.nio.channels.FileChannel.open(FileChannel.java:335) ~[?:1.8.0_252]
at adp.a(SourceFile:37) ~[minecraft_server.1.16.1.jar:?]
at dae$a.<init>(SourceFile:280) ~[minecraft_server.1.16.1.jar:?]
at dae.c(SourceFile:268) ~[minecraft_server.1.16.1.jar:?]
at net.minecraft.server.Main.main(SourceFile:118) [minecraft_server.1.16.1.jar:?]

I downloaded my friends world to put on my server and when I renamed the folder to world, to use, this error came up. However the world works normally on its original world. How do I fix this?