How to login with your Minecraft account:

If you play on Minecraft Java Edition, enter the username of your java account. This should be the username displayed when you type in chat, which should also be in the bottom right corner of your Minecraft Java Launcher! (Ex. FR3shlol)

If you play on Minecraft Bedrock Edition, and want to login with a Bedrock account, this username should be on the right side of the Minecraft Bedrock menu, above the skin of your character.