Let’s begin with the Community forum which is separate from IDE/ST app login. So that password can’t be used for the other two.
Questions - you failed to mention if you are able to login to the ST app? I am assuming that you can’t. Which hub do you have? I want to rule out that you don’t have the orginal v1 hub which has been discontinued in the past few years. If you have a v2 hub released in 2015 then you are OK.
If your SmartThings account did not get migrated to a Samsung account then you will need to contact ST support directly to see if the account was automatically migrated or if they can assist with accessing the data.
Final bit - IDE will be shutdown by December 31, 2022. ST is in the final stages of migrating from Groovy to Edge and Edge does not require the IDE. It is done within the app or by using CLI. Big Change! At this time, you basically only remove groovy code… you can’t add or edit anymore.