I'm trying to install the new version of the do-agent following the tutorial.
first I remove the old do-agent package
then I try to execute curl -sSL https://insights.nyc3.cdn.digitaloceanspaces.com/install.sh | sudo bash

running this command returns me an error:

Cleaning up old sources...OK
Verifying machine compatability...OK
Verifying compatability with script...OK
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package do-agent
Installing apt repository...
E: Failed to fetch http://ppa.launchpad.net/nijel/phpmyadmin/ubuntu/dists/bionic/InRelease  403  Forbidden [IP: 91.189.95.83 80]
E: The repository 'http://ppa.launchpad.net/nijel/phpmyadmin/ubuntu bionic InRelease' is not signed.
Installing gpg key...OK
E: Failed to fetch http://ppa.launchpad.net/nijel/phpmyadmin/ubuntu/dists/bionic/InRelease  403  Forbidden [IP: 91.189.95.83 80]
E: The repository 'http://ppa.launchpad.net/nijel/phpmyadmin/ubuntu bionic InRelease' is not signed.

I am running a 18.04 Ubuntu VM.

Can someone help me solving the problem?
Thank you in advance,

Simone