Excuse me, can Adobe's Siyuan black body be commercially available for free?

You can use it for free, but there are some requirements:

You must attach the Apache protocol to the product; If the code is modified, these modifications need to be noted in the modification file; In the derivative code, it is necessary to indicate the agreement, trademark and patent statement of the original code and the description required by the original author; The readme file (if any) of the product needs to contain Apache protocol, and Apache protocol shall not be modified in the readme file.