A common Google Analytics to Okiano connectivity issue relates to Missing Analytics admin permission.
Check your permission on Google Analytics account, clicking on ‘Admin’ and ‘Account User Management’ to verify you have permission to ‘Edit, Collaborate, Read & Analyze, and Manage Users’.
Sometimes, the connectivity is established even though an error message was displayed. to verify this, check that the email address firstname.lastname@example.org is registers as having permission on the ‘Admin’ and ‘Account User Management’, see picture below.
If you see it there, then the connection should be working properly and the error message was in error.
In case you can't see that email address, please return to your Okiano account and attempt to connect again.
If the problem persists please send an email to email@example.com including a screenshot of the error message you are receiving.