Hello,
I have tested your plugin user verfication at one site and there it works fine.
I am now trying to use it at a second site and here I have some trouble. Email will be sent and link works fine, but the activation key is always invalid.
Here is my last try. Hopefully you can take a look and check this. Thank you in advance:
<a href="https://mv.plus/en/sign-up-page/?activation_key=3f3459d2c698bae21fbc073e6e6b48b9">https://mv.plus/en/sign-up-page/?activation_key=3f3459d2c698bae21fbc073e6e6b48b9</a>
Site is under developement at the moment. You can test by yourself and sign up.
I have to mention that this is a wordpress multisite installation. My first site with user verification plugin is at same installation and I just duplicated the site with a site duplication plugin. But everything else works fine. Just user verification not.
I know, this is a free plugin and therefore support could be limited. I am willing to pay for you help if necessary.
So, please could you take a look and maybe it is just a small case for you.
Thank you in advance and best regards
Holger

Welcome to our forum.
Do you use any other plugin for email verification? or is this multi site network?
Regards
Sorry for late reply, i am from Bangladesh, we haven't tested our plugin in multi-site, multi-site has built-in email verification system.
Regards