The main reason you can not sign up is that you might have not confirmed your email address yet.
Sign Up with Facebook:
From the Sign up page you need to click the Facebook Icon.

Fill in your information and log in:

After that you need to give access to Publer from your Facebook:

Doing that will redirect you to resend the confirmation email:

On your email that you have Facebook connected to you will find an email like below:

Click on it and you will be redirected to Publer. You will be logged in:

Same procedure follows for Twitter. If you did not got the confirmation email you can resend it here: Resend Confirmation Email
Sign Up with Facebook:
From the Sign up page you need to click the Facebook Icon.

Fill in your information and log in:

After that you need to give access to Publer from your Facebook:

Doing that will redirect you to resend the confirmation email:

On your email that you have Facebook connected to you will find an email like below:

Click on it and you will be redirected to Publer. You will be logged in:

Same procedure follows for Twitter. If you did not got the confirmation email you can resend it here: Resend Confirmation Email
Updated on: 12 / 07 / 2022