Tried to install standard Firefox (non-ESR), but can't create a desktop launcher

I realized that the Firefox version that comes pre-installed with Debian 10 is the ESR and not the regular one, so I wanted to get it in order to get the newest features. I followed this video(https://invidio.us/watch?v=8IhGh-lchug) and used this wiki(https://wiki.learnlinux.tv/index.php...x_in_Debian_10) alongside. I followed every step, but when I finish there's no launcher that I can find, the only way for me to use it, is by going to ~/opt/firefox/firefox and clicking the executable.

Did I do something wrong?

Here's the directory where my main firefox folder is located: ~/opt/firefox/firefox
Here's the directory where my .desktop is located: ~/usr/share/applications/firefox-custom.desktop

This is what's inside of my firefox-custom.desktop:

[Desktop Entry]
Version=1.0
Name=Firefox Web Browser
Comment=Browse the World Wide Web
GenericName=Web Browser
Keywords=Internet;WWW;Browser;Web;Explorer
Exec=/opt/firefox/firefox %u
Terminal=false
X-MultipleArgs=false
Type=Application
Icon=firefox
Categories=GNOME;GTK;Network;WebBrowser;
MimeType=text/html;text/xml;application/xhtml+xml;application/xml;application/rss+xml;application/rdf+xml;image/gif;image/jpeg;image/png;x-scheme-handler/http;x-scheme-handler/https;x-scheme-handler/ftp;x-scheme-handler /chrome;video/webm;application/x-xpinstall;
StartupNotify=true
Actions=new-window;new-private-window;

[Desktop Action new-window]
Name=Open a New Window
Exec=/opt/firefox/firefox -new-window

[Desktop Action new-private-window]
Name=Open a New Private Window
Exec=/opt/firefox/firefox -private-window

Any ideas? Thanks a lot!