Dear Antoine
@Antoine
I can confirm that Woocommerce Payments can be installed & updated:
Screen Shot 2022-02-22 at 8.12.56 PM.png
Wordpress, Lay Theme & Laytheme's Addons are all up to date ?
Any custom CSS or JS that may interfere is temporarily removed.
Any third-party plugins are de-activated to see if this resolves the issue.
In regards to the missing template, this is know about but should not be a problem (mine also has this):
Screen Shot 2022-02-22 at 8.12.41 PM.png
http://laythemeforum.com:4567/topic/6784/lay-theme-contains-outdated-copies-of-some-woocommerce-template-files?_=1645514114243
http://laythemeforum.com:4567/topic/6726/review-order-php-outdated/3
Best
Richard