For future people this was the suggestion given to me elsewhere that worked:
Go to terminal and execute this:
keytool -genkey -v -keystore release.keystore -alias yourKeyAlias -keyalg RSA -sigalg SHA1withRSA -keysize 2048 -validity 10000
It will create a file called release.keystore after it asks you some questions.
This is the file you will need to use. yourKeyAlias is the username in Godot and the password will be created with the questions it asks you later.
That file solved my problem. I hope that helps others.