Getting a dump of a mongodb instance

Question

Hey, I'm trying to get a dump of a mongo db. 
```mongodump --uri="mongodb://mongo:@roundhouse.proxy.rlwy.net:/" --out dump20240421 --verbose```
It sort of starts doing something, but after 2 hours I don't see any more disk usage or any other proof that something is happening. What am I doing wrong?
Btw. another option I tried was this:
```mongodump  --authenticationDatabase admin --db lichess --out dump20240421```
But I got this error message

```2024-04-21T10:07:14.590+0200    positional arguments not allowed: []
2024-04-21T10:07:14.590+0200    try 'mongodump --help' for more information```