Failed to open Cisco WebEx meeting using Java Web Start

Question

To enter a college class I need to execute a JNPL file using the command line (because audio doesn't work from Chrome or Firefox):

user@computer:~$ sudo javaws '/home/user/Downloads/CiscoWebExServlet' 

Unfortunally, Instead of getting inside the meeting I get an error:
Evidence is here: Pictures
Also, here is the terminal message when I tried to load the file:

 user@computer:~$ sudo javaws '/home/user/Downloads/CiscoWebExServlet' 
[sudo] password for user: ****

selected jre: /usr/lib/jvm/default-java
WARNING: package javax.jnlp not in java.desktop

Iced Tea is initializing, when It's finally laoded I get the following message in the Terminal:

Unable to use Firefox's proxy settings. Using "DIRECT" as proxy type.
sun.misc.Launcher not found. Running jdk9 or higher? Using unsecure BootClassLoader
Codebase matches codebase manifest attribute, and application is signed. Continuing. See: http://docs.oracle.com/javase/7/docs/technotes/guides/jweb/security/no_redeploy.html for details.
Starting application [JDownload] ...
Sep 16, 2020 2:01:54 PM JDownload main
INFO: Webex java-service JNLP application start...
Sep 16, 2020 2:01:54 PM JDownload getCommandLine
INFO: Webex java-service JNLP application parameters:
     aHR0cHM6Ly91bmlhbmRlcy53ZWJleC5jb20vdW5pYW5kZXMvam1mX3dlYi5waHA/QVQ9VEMmY29uZmlkPTE3MjU1OTY1NjQwMTUxMTM1MyZ1aWQ9LTg5ODI5NzEyJmZsYWc9MHwwJmpubHA9MSZlbWFjPVNESlRTd0FBQUFTVkF4bU9KVEUxRFRmX3ZFUkE1SGFWT1QxeDFYLTVUTE96aU5FMUJQQnItQTI=, https://uniandes.webex.com/client/T33L/javaclient/training/, .webex, T33_TC
JDownload version 2020.06.04.4006.0200
Java version: 11.0.8
Java home: /usr/lib/jvm/java-11-openjdk-amd64
OS name: Linux
OS arch: amd64
OS version: 5.4.0-47-generic
[JDownload]getParameter: pname = ParmArchive return
    https://uniandes.webex.com/client/T33L/javaclient/training/
[JDownload]Decode: str=https://uniandes.webex.com/client/T33L/javaclient/training/ return
    https://uniandes.webex.com/client/T33L/javaclient/training/
[JDownload]Java Client Service home: https://uniandes.webex.com/client/T33L/javaclient/training/
[JDownload]getParameter: pname = GpcProductRoot return
    .webex
[JDownload]Decode: str=.webex return
    .webex
[JDownload]getParameter: pname = GpcProductVersion return
    T33_TC
[JDownload]Decode: str=T33_TC return
    T33_TC
[JDownload]Production home: /root/.webex/T33_TC
[utils.CKit]### cache put key=JAPPLET_INST
    value=JDownload[panel0,0,0,0x0,invalid,layout=java.awt.BorderLayout,rootPane=javax.swing.JRootPane[,0,0,0x0,invalid,layout=javax.swing.JRootPane$RootLayout,alignmentX=0.0,alignmentY=0.0,border=,flags=16777673,maximumSize=,minimumSize=,preferredSize=],rootPaneCheckingEnabled=true]
XXX Failed to request URL: https://uniandes.webex.com/uniandes/jmf_web.php?AT=TC&confid=172559656401511353&uid=-89829712&flag=0|0&jnlp=1&emac=SDJTSwAAAASVAxmOJTE1DTf_vERA5HaVOT1x1X-5TLOziNE1BPBr-A2
Sep 16, 2020 2:01:55 PM JDownload run
SEVERE: Failed to download client parameter!
utils.JCKit$WbxJCStartError: Failed to download client parameter!
    at utils.JCKit.initJCKit(JCKit.java:182)
    at JDownload.initJCKit(JDownload.java:443)
    at JDownload.run(JDownload.java:239)
    at java.base/java.lang.Thread.run(Thread.java:834)

Edit #1: Before today, the teacher created the WebEx meeting from the internet browser directly (which worked perfectly), however he had connection issues, so the University itself decided to make a different alternative (which is the one I cannot open from browser directly).

Edit #2: When I close the dialogue from the error I get:

    Sep 16, 2020 2:26:08 PM JDownload destroy
INFO: destroy.
java.lang.Exception: destroy debug
    at JDownload.destroy(JDownload.java:1137)
    at JDownload.onAppError(JDownload.java:1343)
    at JDownload.run(JDownload.java:380)
    at java.base/java.lang.Thread.run(Thread.java:834)

Sep 16, 2020 2:26:08 PM JDownload destroy
INFO: destroy...