Permission denied in Postgres
You've granted CREATE, CONNECT, and TEMPORARY privileges on the database to myuser but you haven't granted SELECT and INSERT table privileges yet. You'll need something like:

GRANT ALL PRIVILEGES ON ALL TABLES IN SCHEMA public TO myuser;


In addition you need privileges on sequences if you have any serial columns or other column defaults drawing from sequences. Generally, the USAGE privilege is be enough for INSERT operations to work, but since you asked to "give all rights":

GRANT ALL PRIVILEGES ON ALL SEQUENCES IN SCHEMA public TO myuser;


Details on GRANT in the manual.