I think this module is no more updated with recent API updates and also not compatible with SCA requirements.
Might be @mfoland is not aware of this updates from payment gateway.
Let us know if anyone wants help regarding the same.
Thanks for your reply. I am pleased to inform you that we are actually in the process of revamping and enhancing our version of Square Gateway, and in fact we intend to soon offer two versions of this module. V1 - Single payments and V2 - Single and Recurring payments.
Please stay tuned for our next release.
We think this is not official module by Paddle.com for WHMCS, which seems incomplete here to download as free.
Some one just added a sample gist on https://gist.github.com/whitej031788/eb16a3b5ab12f7e1155f6b425e6a1a28
which seems Paddle.com is not serious about providing solutions for their customers.
We @Logicmaker, already providing complete and working module for all latest versions of WHMCS.
You can ask for same at firstname.lastname@example.org or www.logicmaker.in
For anyone that is interested, this module has been confirmed to work properly. It is provided "as is", so certainly could require edits to the PHP files depending on the WHMCS instance, or based on the billing model that is being used.
My attempt to provide a "free example" to help interested developers has unfortunately elicited reviews like this one, who will most likely provide a similar module to this one at a high price. For any PHP developers that are happy taking this module, reading the WHMCS and Paddle documentation and tweaking it to their own needs, this should be sufficient.