If you're trying to connect the Salesforce integration in Retently and instead of accessing the integration's segments page you are redirected back to the Integrations page, then you may not have the required permissions to authorize Retently in your Salesforce workspace.
Follow the tutorial below to learn how to adjust the permissions settings in Salesforce (or ask your Salesforce manager to do this):
In your Salesforce Setup category, navigate to the Manage Connected Apps page, find Retently, and click Edit. Under the OAuth policies section, Permitted Users is (most likely) set to "Admin approved users are pre-authorized".
1. To allow access to this app for a particular group of users:
Leverage "Manage Profiles" and the Profiles related list to authorize access to the appropriate Salesforce profiles (and associated users).
Alternatively, Leverage Permission Sets and the Permission Sets related list to authorize access at a more granular level.
2. To allow access to this App for all users:
Under the OAuth policies section, set Permitted Users to "All users may self-authorize".