The extension is installed om Magento 2.2.3 but not working as expected.
I have done the email template and it should be displayed on the product page but the email subscribe is not displaying.
It is showing on the category page, but that button takes you to the product and then no email field?
The issue is caused due to the fact that your Magento ver 2.2.3 does not have the module MSP_ReCaptcha (MSP_ReCaptcha only has from Magento ver 2.3.x and above).
Hence, to fix the issue, we would suggest removing all the parts related to module MSP_ReCaptcha, so your site will not use this config Use Default reCaptcha.
To do that, please check and edit two files:
Please check and replace two changed files on your site. And then flush the cache.
If you need any further support, please feel free to contact us.