Paypal: No Guest Checkout

-- HikaShop version -- : 4.4.5
-- Joomla version -- : 4.0.4
-- Browser(s) name and version -- : Chrome

Dear HIKA-Team,

I have installed the classic PayPal plugin from HIKA-Shop with a sandbox account (but same problem with live account). When entering the PP page during checkout, I don't see the guest checkout button for direct credit card payment. I have activated it in PP (PayPal account optional) and my e-mail address is activated.

BUT: A PP robot told me that the following might be an issue, since I am using a 3rd-party plugin. My question concerns the second part with "SOLUTIONTYPE=Sole" and if I need to activate it somewhere?!?

Guest Checkout Requirements
Before you can enable Guest Checkout in Checkout, you’ll need to meet the following requirements:
Have a confirmed email address.
Set PayPal Account Optional to On within your PayPal settings (see below).

With a Checkout custom-coded solution, there is an additional step:
Set SOLUTIONTYPE=Sole in your initial SetExpressCheckout API call.
If you’re using a third-party shopping cart, you’ll need to work with them or your developer to implement this variable.
As long as SOLUTIONTYPE=Sole is passed in the SetExpressCheckout API, Guest Checkout will be enabled.
In order for SOLUTIONTYPE=Sole to work, you must have PayPal Account Optional set to On within the PayPal account settings (see below).
Many third-party carts provide an Enable Guest Checkout option in the Administration view of their Checkout module.

This comes from site: www.paypal.com/us/smarthelp/article/how-...ckout-option-faq3226

Merci et tout de bon,
Martin