Thanks for your effort @James Hamil . Appreciate it.
It seems that the stringId that I used in the above snippets is not for api.signuporsignin but it should be used in conjunction with api.selfasserted. This information was hidden here
I changed this to the following and it worked :)
<LocalizedResources Id="api.selfasserted.en">
<LocalizedStrings>
<LocalizedString ElementType="UxElement" StringId="ver_intro_msg">Please verify your email address.</LocalizedString>
<LocalizedString ElementType="UxElement" StringId="button_continue">continue</LocalizedString>
<LocalizedString ElementType="UxElement" StringId="ver_but_send">Send verification code to email</LocalizedString>
</LocalizedStrings>