In Postmypost, go to the "Accounts" section and click "Connect".
In the opened window with the list of social networks, click "Connect" next to Threads.
A window will open for the official connection of the Threads account to Postmypost, which will specify what data and permissions are required by Postmypost to operate. Ensure you agree to provide access and click "Continue".
After successful connection, you will automatically return to Postmypost, where a list of available accounts to connect will appear. Check the box next to the desired ones and click "Connect".