Each service asks for something a little different when you connect it on the Integrations and AI tab, under Your autoresponder. The steps for finding the key also appear on screen, right under the service picker. Here is the short version, service by service.
AWeber, the full connection:
Click Open AWeber, log in, click Allow, copy the code AWeber shows you, paste it and click Connect. If the form also asks for an AWeber app Client ID, that is a one time step: create a free app at labs.aweber.com, choose Public client, use the redirect URL shown on screen and paste the Client ID it gives you. Tags are real AWeber tags and are added to returning subscribers too. You pick a list on each survey, and one is needed.
AWeber, simple with no login:
You need your list's unique list ID, found in AWeber under List Options, then List Settings. It looks like awlist followed by digits. There is an optional Ad tracking value, which shows in AWeber as where the subscriber came from. Tags are real AWeber tags. The sign-up is sent by your visitor's browser, so it cannot be retried or confirmed here. For retries, a record of every send and a list per answer, use the full connection.
Mailchimp:
Create an API key in your profile under Extras, then API keys. In Mailchimp a list is called an audience, and you pick one on each survey. Tags are real tags. Tick the box on the connection if you want Mailchimp's confirmation email sent first; left unticked, people are added straight away.
ActiveCampaign:
Under Settings, then Developer, copy the API URL and the API key. A list is optional, so tags alone will do. Commas inside a tag are turned into spaces, because ActiveCampaign does not allow them in tag names.
Kit (ConvertKit):
Under Settings, then Developer, add a V4 API key. Older V3 keys do not work here. In Kit people join a form, so your forms appear as the lists to pick from. Tags are real tags.
GetResponse:
Generate an API key under Tools, then Integrations and API, then API. GetResponse switches off keys that have not been used for 90 days, so if sending stops after a quiet spell, paste a fresh key. Its tags can only hold letters, numbers and underscores, so spaces and dashes in your tags become underscores there. A list is needed.
Brevo:
Generate an API key under SMTP and API, then API keys. Brevo has no tags, so each tag becomes a list called Tag: followed by your tag, kept in a folder called ResultsAiX Survey tags.
SendFox:
Create a Personal Access Token under Settings, then API. The SendFox API needs a Lifetime or Empire plan. SendFox cannot tag a contact from outside, so each tag becomes a list called Tag: followed by your tag.
Systeme.io:
Create a key under Profile settings, then Public API keys. Systeme.io has no lists, it uses tags, so set the tags on each survey and start your Systeme.io automations from those tags.
HighLevel (GoHighLevel):
In the sub-account, open Settings, then Private Integrations, and create one with the scopes contacts.write, contacts.readonly, locations/tags.readonly and locations/tags.write. Copy the token it shows, which appears only once. The Location ID is under Settings, then Business Profile. HighLevel has no lists here, so use tags to start your workflows.
LeadsLeap (SendSteed):
In SendSteed, pick a list, click Get Code and scroll to Third Party Source Code. Your username is the lluid value and each list's id is its lllid value. Type your lists in one per line, as the list id, an equals sign and a name you will recognise. LeadsLeap cannot tag a contact from outside, so make a list in LeadsLeap for each tag you want and match them up in the Tags that stand for a list box, one per line, as the tag, an equals sign and the list id. LeadsLeap always sends its own confirmation email.
Any other service, through its sign-up form:
Open the HTML version of your service's sign-up form and copy three things: the address after action=, the name of the email box and the name of the first name box. If your service reads tags from a form field, name that field and the survey's tags are sent in it, comma separated. Any hidden fields the form needs, such as a list id, go in the extra fields box, one per line, like listname=mylist.
Whichever you use, click Send a test contact with your own address and check the contact arrived in your service with the right list and tags.