Rstudio server not starting in browser

I connected a GCP VM to my local machine and installed RStudio per this tutorial: https://towardsdatascience.com/r-studio-server-on-google-cloud-dd69b8bff80b

However, when I try to access RStudio server on chrome using http://external-ip:8787 I get a "took too long to respond error.

1. My installation was successful.
2. I checked the firewall settings on GCP and it's configured correctly to port 8787.
3. This is the current status:

● rstudio-server.service - RStudio Server
   Loaded: loaded (/lib/systemd/system/rstudio-server.service; enabled; vendor p
   Active: active (running) since Tue 2021-07-06 21:56:00 UTC; 31min ago
  Process: 8290 ExecStop=/usr/bin/killall -TERM rserver (code=exited, status=0/S
  Process: 8446 ExecStart=/usr/lib/rstudio-server/bin/rserver (code=exited, stat
 Main PID: 8447 (rserver)
    Tasks: 3 (limit: 4915)
   CGroup: /system.slice/rstudio-server.service
           └─8447 /usr/lib/rstudio-server/bin/rserver

Jul 06 21:56:00 datascience-2 systemd[1]: Starting RStudio Server...
Jul 06 21:56:00 datascience-2 systemd[1]: Started RStudio Server.

Could someone please help me resolve this?