Well… in the main menu is a button called “account” and I clicked on that, created an account on account.secretworldlegends and linked that with steam. It also says “Account Type: Steam”, this was also stated in the account on secretworldlegends before I made my character.
This is everything I had done yesterday, after that I created my character and started playing.

Today I started the game via Steam and the game suggested that I create a character, which is strange because I had one, the one that I logged off with yesterday.