Steps

1. Go to Gmail
2. https://mail.google.com/mail/u/0/#inbox
3. Select the desired account
4. At the top right, on the website (not the browser), click on the colored circle with the first letter of the account
5. Click on the one you want, or add the one you need to be able to select it
6. Activate the "Less secure access of applications"
7. Click on the colored circle with the first letter of the account
8. Click on "Manage your Google Account"
9. Go to the "Security" category in the left menu
10. Scroll down until you see the "Less secure access to applications" section
11. Click on "Activate access (not recommended)"
12. Activate the switch to confirm
13. Close tab
14. Activate the "IMAP" connection
15. Click the settings wheel in Gmail
16. Click on "Settings"
17. Go to the "Transfer and POP / IMAP" tab
18. Activate "IMAP access" (check that the message has turned green)
19. Close tab
20. Add the account in Outlook
21. Go to Outlook
22. Click on "File" -> "Add an account" -> Fill with the identifiers of the newly modified Gmail account