hello,
Welcome to the WPLMS support.
Tip: For better support always share a screenshot:
Please provide the proper screenshot, use https://prnt.sc/ to upload and share the URL of the screenshot.
If you want to send us a video of the issue, use https://screencast-o-matic.com/ to upload and share the URL of the video.
please share your site url and admin credentials, for sharing your admin credentials always send them as a private reply by using this: http://prntscr.com/qicf9i
for your issue you can refer to this tip:
https://wplms.io/support/knowledge-base/custom-activation-registration-emails-for-registration-forms/
The activation email is sent by the buddypress plugin.
The exact reason why your emails are not sending can be explained by your webhost only.
If you have your cpanel credentials then you can go there and go to WHM and see which email is not sent and why it is failed.
The request is in the pending, this means the buddypress tried to send the email but for some reasons it is not sent and this you can see in the WHM.
On our test setups we use WP SMTP , refer: https://wplms.io/support/knowledge-base/wplms-mail-smtp-gmail-smtp/