When trying to add a bot, the user checks the URL in the gear on the bottom right of the Bot and makes sure it matches the URL for RPA Central. Then clicks "Request Access" and the request never makes it to RPA Central.
There may not be ab error code.
When the machine is first booted and RPA Bot is launched, you should see Foxtrot64, Nintex Bot, and RPA Starter in the Task Manager. The first time a browser is opened and navigated to a page, Nintex RPA Chromium Channel should start if it didn't start already when you launched the Bot.