You can set up Single Sign On (SSO) between your Bubble.io website and your Website Toolbox Forum by following the steps below:

1. Visit Bubble.io website.
2. Log in to your Bubble.io account admin panel.
3. Launch the editor of the app where you want to set up an SSO.
4. Click the Settings button in the left panel.
5. Select API on the top.
6. Check the checkbox next to User.
7. Select Page_login from the drop-down next to the Login page for SSO/OAuth redirects.
8. Click the Add a new 3rd party app button.
9. Type SSO Forum or any desired text in the Name text box.
10. Log in to your Website Toolbox account.
11. Click the Integrate link.
12. Click the Single Sign On link.
13. Select Custom OAuth in the website builder drop-down.
14. Copy the redirect/callback URL.
15. Return to the Bubble.io page and paste the callback URL copied above.
16. Copy the Client Id, and Client Secret into a notepad.
17. Return to Website Toolbox and paste the Client Id, and Client Secret
18. For Authorization URL, add your website URL followed by api/1.1/oauth/authorize) (i.e.: https://yourwebsiteURL.com/api/1.1/oauth/authorize).
19. For Access Token URL, add your website URL followed by api/1.1/oauth/access_token) (i.e.: https://yourwebsiteURL.com/api/1.1/oauth/access_token).
20. For User Data access URL, add your website URL followed by api/1.1/oauth/user) (i.e.: https://yourwebsiteURL.com/api/1.1/oauth/user).
21. Click Save.
22. Go back to the Bubble.io website page, click on the Main link on the top, and click the Deploy to Live button.