Blynk Install for Raspberry Pi Update

I am trying to install Blynk onto my Raspberry by following the instructions for it on:

(Documentation for Blynk, the most popular IoT platform for businesses.)

And when I reach the part where I must enter the command “sudo npm install -g onoff”, I get this message:

WARNING: You are likely using a version of node-tar or npm that is incompatible with this version of Node.js.
Please use either the version of npm that is bundled with Node.js, or a version of npm (> 5.5.1 or < 5.4.0) or node-tar (> 4.0.1) that is compatible with Node.js 9 and above.
npm[1577]: …/src/node_zlib.cc:568:static void node::{anonymous}::ZlibStream::Init(const v8::FunctionCallbackInfov8::Value&): Assertion `args.Length() == 7 && “init(windowBits, level, memLevel, strategy, writeResult, writeCallback,” " dictionary)"’ failed.
Aborted

I think the install method for raspberry might be outdated and I ask if there is an updated install version coming soon, or I might have a problem with my raspberry, can anyone help?

You should be following these instructions…

But, I use Java 11 on my Pi 4 so I use server-0.41.15.jar rather than server-0.41.15-java8.jar

Also, because the latest server version is 0.41.15 you need to need to use this instead of 0.41.13 in commands like this:

wget "https://github.com/blynkkk/blynk-server/releases/download/v0.41.13/server-0.41.13-java8.jar"

Pete.