"Not a directory" error

Just installed Lubuntu on my laptop. Win8 was the only previous OS on it.

After that I tried install slimjet following this:

https://linuxways.net/ubuntu/how-to-install-slimjet-browser-on-ubuntu-20-04/

But I couldn't since some "not a directory" error happened after CD and dpkg commands didn't work.

This is from my terminal(strangely enough it can recognize 'ls' command and bring the folders, but it won't do the same for typed or even copied paths! )

none0@none0-X102BA:~$ cd ~/Downloads/slimjet_amd64.deb
bash: cd: /home/none0/Downloads/slimjet_amd64.deb: Not a directory
none0@none0-X102BA:~$ ~/Downloads$ ls
bash: /home/none0/Downloads$: No such file or directory
none0@none0-X102BA:~$ cd /home/none0/Downloads/slimjet_amd64.deb
bash: cd: /home/none0/Downloads/slimjet_amd64.deb: Not a directory
none0@none0-X102BA:~$
none0@none0-X102BA:~$ ls
Desktop Downloads Music Public Videos
Documents mozilla.pdf Pictures Templates
none0@none0-X102BA:~$ Downloads
Downloads: command not found
none0@none0-X102BA:~$ cd /home/none0/Downloads/slimjet_amd64.deb
bash: cd: /home/none0/Downloads/slimjet_amd64.deb: Not a directory
none0@none0-X102BA:~$ cd /home/none0/Downloads/slimjet_amd64.deb
bash: cd: /home/none0/Downloads/slimjet_amd64.deb: Not a directory
none0@none0-X102BA:~$ sudo dpkg -i slimjet_amd64.deb
[sudo] password for none0:
dpkg: error processing archive slimjet_amd64.deb (--install):
cannot access archive: No such file or directory
Errors were encountered while processing:
slimjet_amd64.deb
none0@none0-X102BA:~$ rr
The program 'rr' is currently not installed. You can install it by typing:
sudo apt install rr

The instructions on that page is wrong!

The correct commands is:

cd ~/Downloads

cd stands for change directory. Downloads is the directory.

Once you complete the above command, you enter the next one:

sudo dpkg -i slimjet_amd64.deb

You will be asked to enter your password. When you type the password nothing will show on the terminal. This is normal.

Uninstall

If you don't like the software and want to uninstall it, use the following command:

sudo apt remove slimjet

Another way to uninstall it is to open the Ubuntu Software Store and search of the slimjet. It should be listed as an installed software, and clicking on the Remove button will remove it.

In either case you will need to enter your password.

See How can I uninstall software? for more on uninstalling software in Ubuntu.

Hope this helps