Don’t wary this is not your fault or not your website issue but this is a knowing issue in all the versions of Magento 2.3.5 and less.
Magento does not allow adding the grouped product to the Requisition list and if you add it then you will see this type of error message in Magento version 2.3.5 and less.
Options were updated. Please review available configurations issue is already solved in Magento 2 latest version. This error is solved in Magento B2B version 1.3.1, you can review the detailed release note from here. From this B2B version, Magento allows adding the simple products of grouped product from the grouped product page.
Solution: So to solve this error either you can install a patch file or you can simply upgrade your Magento 2 version and you can add grouped products to the requisition list.