PHPSESSID is for PHP’s session data (different from cookie data) and is not for verifying login credentials. You shouldn’t really need to be setting that cookie, PHP will handle it on its own.
Question: Why do you need to login with auth.roblox.com/v2/login if you’re storing the .ROBLOSECURITY cookie anyways? That bypasses login completely, even with 2FA enabled.
If you’re not storing the cookie in your application, and are getting it from the login post request, then what you are doing is correct, just rename PHPSESSID to the .ROBLOSECURITY cookie name used for local login storage, and be sure to set the cookie to the .ROBLOSECURITY cookie that your login post request will have created.
Yes but that started a few minutes ago, this is irrelevant to his problem (posted over an hour ago).
I actually ended up finding a solution a long time ago, based off of the robloxapi module, and figured out how to make it work. I just forgot to mark the solution.
I really appreciate the great resource though. Thanks!