In order to add google reCaptcha in admin panel (Settings => General Settings) please do the following:
1) Go to this link: https://www.google.com/recaptcha/intro/v3.html (log in if you're not) You might see an option on top right that says "Admin Console" click on that.
2) Locate the plus "+" sign on the right
3) Type out a label. It could be the name of your website. Just something to remember this reCaptcha
4) Next choose any of the reCaptcha types
5) Now, type out your domain name (eg. example.com)
6) Finally Accept Terms of Service and hit submit
7) Once that is done, copy the reCaptcha key and secret and paste in backend admin panel (so Settings => General Settings)
Where does this (Google reCaptcha) show up? It shows up in support page (https://www.gigtodo.com/customer_support) before customer submits it.