@dos Yeah, forge uses nginx for web server. I would not recommend running both apache and nginx, mostly since you will only be able to run one on port 80.
But you know, here's an alternative. I take it you already have a laravel site on forge right? And probably under nginx already? If so do this. Go into the "public" folder of the laravel site and create a new folder in there to hold the adminer php file. So line make a folder called "adminer" under public, place the file in there, and rename it to "index.php". Then, after you go into that file and fill in the settings, you will be able to access it as:
Anything inside the "public" dir gets processed as-is. So this works. Just tried it on one of my sites.
That's a quick and dirty way to get it up without having to mess with your webserver. The correct way, if you want it separate, it to set up another site under nginx and point it to a directory with the adminer file. I would also choose a more cryptic name for the directory so it is harder to find, and maybe even look into htpasswd authentication or IP based blocks on that directory.
But this should get you going.