Unable to install NordVPN on Ubuntu Mate 20.04

Cannot manage to install NordVPN.

Tried:

sudo apt-get install nordvpn

Got back:

E: Unable to locate package nordvpn

I've read the following 2 questions and answers this and this, I've tried to dpkg the .deb file, but the solutions did not work.

If I ran sudo apt update without this line:

deb [arch=amd64] stable main

I get no errors, but this results in no installation package.

If I add the line above (it is a 64bit system), I get the following:

Err:6 stable InRelease
Connection failed [IP: 90.255.255.14 80]
W: Failed to fetch Connection failed [IP: 90.255.255.14 80]
W: Some index files failed to download. They have been ignored, or old ones used instead.

I can use OpenVPN, but it'd be much smoother to just use the NordVPN client.

Thanks in advance ^.^

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