ARMember Wordpress: Not assigned a data plan after payment

I use the purchased ARMember membership plugin for WordPress. I set up the payment gateway, and did everything as per the instructions. I use the Robocass plugin+Woocommerce. The payment goes perfectly, in the ARMember logs it is written that the payment was made successfully, but the membership is not automatically assigned. There is such an error in the WordPress logs:

13-Aug-2020 17:13:21 UTC] PHP Notice: The order_date function was called incorrectly. Order properties should not be accessed directly. Backtrace: require('wp-blog-header.php'), wp, WP->main, WP->parse_request, do_action_ref_array('parse_request'), WP_Hook->do_action, WP_Hook->apply_filters, robokassa_payment_wp_robokassa_checkPayment, WC_Order->payment_complete, WC_Order->save, WC_Order->status_transition, do_action('woocommerce_order_status_completed'), WP_Hook->do_action, WP_Hook->apply_filters, ARM_wocommerce_feature->arm_woocommerce_add_member, ARM_wocommerce_feature->arm_store_woocommerce_log, WC_Abstract_Legacy_Order->__get, wc_doing_it_wrong For more information, see "Debugging in WordPress". (This message was added in version 3.0.) in /home/...../...../...../public_html/wp-includes/functions.php on line 5167

Apparently, this is due to a mismatch of date formats. The robokassa in Woocommerce sends in the Russian format (d:m:Y), and ARMember accepts in the European format (Y-m-d). In the php settings issues:

Ibase.dateformat %Y-%m-%d %Y-%m-%d

Is there any simple way to solve this problem? Or do you need to write a plugin that converts the date on the fly? Only how to do this, technical support is unlikely to give me detailed technical information.

The creators of ARMember themselves write on their website that they now support any date format, but I did not find a way to change it in the admin panel.

Changed the date format in WordPress itself, the result no.

Still, everything is complicated by the fact that the server on which the site is hosted does not issue php logs.

In general, anyone who has encountered or knows how to solve, or knows what the problem is, please help!