Thank you very much! I was able to use the Admin user that was created in this authentification
@Abhinov-Singh-0 I suggest learning about solving Linux permissions issues on your own.
For now, I'm guessing you need to make it executable:
chmod +x ./nodebb
It may also be an issue with ownership, in which case you'd use chown.
You can search for any of these topics and find hundreds of tutorials.