Readiness Check failed on install components

[kenan_kutlu]

Hello,I have the version Magento 2.1.15.

I want to install PayPal Plus and I notice I get a Readiness Check error message. (see the screenshot).
Does anyone have an idea why this might be?

[TutorialMagento]

Please reupload screenshot, I can't see it

[WebHostingAce]

The error you are getting from GUI does not say much.

Please try to use command-line,

#composer require vendor/module

Eg -

#composer require datendampfer/magento2-paypal-plus