If you want to use the remote debugger on linux, just use the enable_debugger and related commands to activate it, after which you can use the modeler to point to the /debugger/ sub-url.
If your application is behind nginx, be sure to proxy_pass the /debugger/ sub-url to the actual application:
m2ee(m2eetest): enable_debugger Please enter the password to be used for remote debugger access from the modeler, or leave blank to auto-generate a password: INFO: The remote debugger is now enabled, the password to use is ofhqa9geHU3bnPTHnEylcscj INFO: You can use the remote debugger option in the Mendix Business Modeler to connect to the /debugger/ sub url on your application (e.g. https://app.example.com/debugger/). m2ee(m2eetest): m2ee(m2eetest): show_debugger_status INFO: The remote debugger is currently enabled. INFO: There is no connected debugger session. INFO: There are no paused microflows. m2ee(m2eetest): disable_debugger INFO: The remote debugger is now disabled.
The admin_pass you're refering to is a local password that's used for communucation between the m2ee client and the runtime as simple authentication to fire requests to the runtime, like the enable_debugger command shown here. You only set it to a long random obscure value and never need to use it anywhere else:
Take a look at this post. I think it has the answer for you.