Ubuntu 20.04 | Citrix workspace app | Working!
I first downloaded the DEB package here and installed the Workspace app a.k.a ICAclient.
After that I connected to the customers website to get into their environment with Citrix. It went pretty well until the .ica file popup showed. I chose to open it with the Citrix workspace... and nothing happened; the Citrix workspace did not start.
Luckely I found this tip by Ritika Argawal.
I first checked if both directories existed. Thus, the directory with the mozilla certificates and where my ICAclient was installed.
Second and last I could setup the command and then execute it:
sudo ln -s /usr/share/ca-certificates/mozilla/* /opt/Citrix/ICAClient/keystore/cacerts
And after that, Citrix workspace started!