Thank you for contacting WPML support, I'd be happy to help you with this issue.
Now I can see the Paypal gateway is available on the checkout page as well. Please check the screenshot attached. Can you please confirm it works on your end?
The minimum requirements are 128M, but we do recommend 256M and the debug information of your site shows it set to 40M. Please check this link for more details https://wpml.org/home/minimum-requirements/.
You can increase it by adding the following code in your wp-config.php file, right before the /* That’s all, stop editing! Happy publishing. */ line: