Explaindio API Login needs your Sign-up Email ID and your Explaindio Member Account Password. Please make sure you've correctly entered your sign-up email ID and your Explaindio Member Account Password (the same password you use to login to your Explaindio Membership area here: https://account.explaindio.com/in/member)
But if you did enter the correctly but you are still getting an error saying "Explaindio API Login Error. Check Credentials" it means you might have a special character in your Explaindio Member Account Password.
Explaindio API Validation is special character sensitive. Any special character in password will fail validation.
So, if you get this error, click Lost Password? link to go to your Explaindio Membership area or login to your Explaindio Membership area here: https://account.explaindio.com/in/member
Click change next to Password and reset your password. Set a new password without any special character in it.
Now go back to Explaindio 4 and enter the new password you've set without any special characters. Click login and this time Explaindio API will accept your validation.