Hello Amine,
You can feel free to use TZ Portfolio with Fancybox3 on your Joomla Template. We have purchased license to use Fancybox3 with TZ Portfolio. Please check the product policies below:
+ You can use TZ Portfolio+ free version for your Joomla template that sold on Themeforest
+ Fancybox3 licensed for only TZ Portfolio. You can use it with TZ Portfolio extension only, not for others 3rd party extension.
+ You can use your template override all TZ Portfolio view according your template design
Furthermore, If you love to use TZ Portfolio for your future Joomla Template you can join strategic partners program of TZ Portfolio. Read more about this program
https://www.tzportfolio.com/blog/invitation-to-collaborate-with-tz-portfolio-for-mutual-benefits.html
Please let me know if you have any question.
Thanks for your support!
Best Regards,
Sonny