The free version should definitely support multisite.
Do you receive this error when adding snippets both on a network level and a subsite level? Or only one of the two?
First added the snippet to multisite’s mainsite, and tried to network activate it. Didn’t work. with aforementioned 500.
Then, I found that it is possible to run it in each subsite. So I tried it on one of the subsites. Worked, but when I try to network activate it from there, again 500.
I can manually activate it to all subsites, since in each subsite, there is a code snippet menu in the admin panel.
After that, I come to understand that not only my custom snippet, but even your base example code snippets don’t get network activated.
If free version is network activatable, then I guess it is related to either my server or one of the other theme/plugins.
Per your suggestion, I’ve also checked with activation on both levels, then I end up with critical error on the webpage.
While keep it activiated at subsite level, I’ve tried to activate it at superadmin site, then I ended up with critical error on my subsite.
I will mark the ticket closed. it isn’t related to your plugin.