Node-Red Install Script not working

Hello,
what can I do if this official node-red install script not working my Pi3 ?

curl -sL https://raw.githubusercontent.com/node-red/linux-installers/master/deb/update-nodejs-and-nodered)

Error Messages are:

(node:1476) [DEP0022] DeprecationWarning: os.tmpDir() is deprecated. Use os.tmpdir() instead. nodes to local
npm ERR! not ok code 1es
Install Node-RED core ?
(node:1514) [DEP0022] DeprecationWarning: os.tmpDir() is deprecated. Use os.tmpdir() instead.emd script

What os/version have you flashed on the SD card?

cat /etc/os-release reports Version "9 (stretch)"
Raspbian.

All OS updates have been installed.

Can you share more of the log? The "errors" you e shared are not errors, just warnings.

But node-red-start reports
"Node-Red-Start is not yet fully installed. Please re-run the install script again"
then same result.

This is content of nodered-install.log:
Started : Sa 13. Jun 12:11:00 CEST 2020
Running for user pi at /home/pi
Found global nodes: :

WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

Paketlisten werden gelesen...
Abhängigkeitsbaum wird aufgebaut....
Statusinformationen werden eingelesen....
Paket »nodered« ist nicht installiert, wird also auch nicht entfernt.
Das folgende Paket wurde automatisch installiert und wird nicht mehr benötigt:
libmicrodns0
Verwenden Sie »sudo apt autoremove«, um es zu entfernen.
0 aktualisiert, 0 neu installiert, 0 zu entfernen und 0 nicht aktualisiert.
Already have nodejs v8.11.1
Now install nodejs
Versions: node:v8.11.1 npm:1.4.21
Now install Node-RED
(node:2425) [DEP0022] DeprecationWarning: os.tmpDir() is deprecated. Use os.tmpdir() instead.
npm ERR! Error: Method Not Allowed
npm ERR! at errorResponse (/usr/share/npm/lib/cache/add-named.js:260:10)
npm ERR! at /usr/share/npm/lib/cache/add-named.js:120:12
npm ERR! at saved (/usr/share/npm/node_modules/npm-registry-client/lib/get.js:167:7)
npm ERR! at FSReqWrap.oncomplete (fs.js:135:15)
npm ERR! If you need help, you may report this entire log,
npm ERR! including the npm and node versions, at:
npm ERR! http://github.com/npm/npm/issues

npm ERR! System Linux 4.19.66-v7+
npm ERR! command "/usr/bin/node" "/usr/bin/npm" "i" "-g" "--unsafe-perm" "--no-progress" "--no-update-notifier" "--no-audit" "--no-fund" "node-red@latest"
npm ERR! cwd /home/pi
npm ERR! node -v v8.11.1
npm ERR! npm -v 1.4.21
npm ERR! code E405
npm ERR!
npm ERR! Additional logging details can be found in:
npm ERR! /home/pi/npm-debug.log
npm ERR! not ok code 0
Now create basic package.json for the user and move any global nodes
Installing extra nodes: node-red-node-pi-gpio node-red-node-random node-red-node-ping node-red-contrib-play-audio node-red-node-smooth node-red-node-serialport :
(node:2504) [DEP0022] DeprecationWarning: os.tmpDir() is deprecated. Use os.tmpdir() instead.
npm ERR! Error: Method Not Allowed
npm ERR! at errorResponse (/usr/share/npm/lib/cache/add-named.js:260:10)
npm ERR! at /usr/share/npm/lib/cache/add-named.js:203:12
npm ERR! at saved (/usr/share/npm/node_modules/npm-registry-client/lib/get.js:167:7)
npm ERR! at FSReqWrap.oncomplete (fs.js:135:15)
npm ERR! If you need help, you may report this entire log,
npm ERR! including the npm and node versions, at:
npm ERR! http://github.com/npm/npm/issues

npm ERR! System Linux 4.19.66-v7+
npm ERR! command "/usr/bin/node" "/usr/bin/npm" "i" "--unsafe-perm" "--save" "--no-progress" "--no-update-notifier" "--no-audit" "--no-fund" "node-red-node-pi-gpio" "node-red-node-random" "node-red-node-ping" "node-red-contrib-play-audio" "node-red-node-smooth" "node-red-node-serialport"
npm ERR! cwd /home/pi/.node-red
npm ERR! node -v v8.11.1
npm ERR! npm -v 1.4.21
npm ERR! code E405
npm ERR!
npm ERR! Additional logging details can be found in:
npm ERR! /home/pi/.node-red/npm-debug.log
npm ERR! not ok code 0
Now add the shortcut and start/stop/log scripts to the menu
Now add systemd script and configure it for pi
Now add launcher to top bar, add cpu temp example, make sure ping works
Der Benutzer »pi« ist bereits ein Mitglied der Gruppe »gpio«.

node-red-start reports "npm-version too old"
install npm reports "You have latest version 1.5.21+ds-2"
what is that mess?

OK, I found solution here:
Both npm and node are not up to date.
sudo npm install -g n
sudo n stable

Don't ask me about meaning of this,
but now Palette Manager working in Node-Red
linux has still not become easier :sweat:

The best solution would be to remove the versions of nodejs and npm (I guess they had somehow got installed from the Raspbian repository before you ran the script) and run the script again. So run
sudo apt-get remove nodejs npm
then run the script again.
However I would also say that running stretch is not a good idea unless you need that version for some reason. It is no longer supported. You should use Buster.