How to change button text?

To change 'continue with phone' text just use the shortcode and change your text like below

[firebase_otp_login phone_toggle_button_text="your text here"]

To change other text please check our docs shortcode parameters section,

1.  'phone_button_text' => default value 'Send Code' 
2.  'code_button_text' => default value 'Verify & Login', 
3.  'phone_toggle_button_text' => default value 'Continue with Phone', 
4.  'recaptcha' => default value 'invisible', // invisible or normal